MFC r306325, r306329-r306330, r306333, r306620-r306622, r307544, r307550, r318137, r319125, r319295

r306325 by marcel:
Replace the use of linker sets with constructors for both the
formats and schemes. Formats and schemes are registered at
runtime now, rather than collected at link time.

r306329 by marcel:
Eliminate the use of EDOOFUS. The error code was used to signal
programming errors, but is really a poor substitute for assert.
And less portable as well.

r306330 by marcel:
Avoid depending on the <sys/endian.h> header for le*enc and be*enc.
Not only is the header unportable, the encoding/decoding functions
are as well. Instead, duplicate the handful of small inlines we
need into a private header called endian.h.

Aside: an alternative approach is to move the encoding/decoding
functions to a separate system header. While the header is still
nonportable, such an approach would make it possible to re-use the
definitions by playing games with include paths. This may be the
preferred approach if more (build) utilities need this. This
change does not preclude that. In fact, it makes it easier.

r306333 by marcel:
Portability changes:
1. macOS nor Linux have MAP_NOCORE nor MAP_NOSYNC. Define as 0.
2. macOS doesn't have SEEK_DATA nor SEEK_HOLE. Define as -1
so that lseek will return -1 (with errno set to EINVAL).
3. gcc correctly warns that error is assigned but not used in
image_copyout_region(). Fix by returning on the first error.

r306620 by marcel:
Replace STAILQ with TAILQ. TAILQs are portable enough that they can
be used on both macOS and Linux. STAILQs are not. In particular,
STAILQ_LAST does not next on Linux. Since neither STAILQ_FOREACH_SAFE
nor TAILQ_FOREACH_SAFE exist on Linux, replace its use with a regular
TAILQ_FOREACH. The _SAFE variant was only used for having the next
pointer in a local variable.

r306621 by marcel:
Prefer <stdint.h> over <sys/types.h>. While here remove redundant
inclusion of <sys/queue.h>.

Move the inclusion of the disk partitioning headers out of order
and inbetween standard headers and local header. They will change
in a subsequent commit.

r306622 by marcel:
Replace OFF_MAX with INT64_MAX. The former is defined on Linux.

r307544 by marcel:
o Provide a private definition for UUIDs (mkimg_uuid_t) because
UUIDs are not portable.
o Move mkimg_uuid() to a new file and merge both gpt_uuid_enc()
and vhd_uuid_enc() into a single mkimg_uuid_enc() that lives
in the same file.
o Move the OS-specific implementation of generating a UUID to
osdep_uuidgen() and provide the implementations for FreeBSD,
macOS and Linux.
o Expect the partitioning scheme headers to be found by having
a search to the directory in which the headers live. This
avoids conflicts on non-FreeBSD machines.

r307550 by imp:
Add a new flag to mkimg (-a num) to specify the active partition for
those partitioning schemes that have this concept. Implement it as an
override for mbr's setting 0x80 in the flags for the first partition
when we have boot code.

Differential Revision: https://reviews.freebsd.org/D4403

r318137:
mkimg: Add -C argument to specify maximum capacity

Add a -C option to specify a maximum capacity for the final image file.
It is useful to control the size of the generated image for sdcard or
when we will add dynamic size partition.

Add --capacity which is a shorthand to define min and max capacity at
the same time.

Reviewed by: bapt, marcel, wblock (manpages)
Sponsored by: Gandi.net
Differential Revision: https://reviews.freebsd.org/D10509

r319125:
mkimg: Correct an off by one error in the PMBR size

The PMBR last sector should be number of sector - 1 (As stated in UEFI Spec
2.6 page 118 table 17).
This fixes warning printed by linux tools like parted or fdisk.

Sponsored by: Gandi.net

r319295 by ngie:
Update the usr.bin/mkimg golden test output files after ^/head@r319125

^/head@r319125 changed the location of the backup pmbr, requiring the
output files to be regenerated, since they're binary disk dumps.

The output files were regenerated with "make rebase"--fixed in
^/head@r319294.

MFC with: r319125, r319294
PR: 219673
Sponsored by: Dell EMC Isilon

Revert r328974, r307387 was not supposed to be part of it.

MFC r306325, r306329-r306330, r306333, r306620-r306622, r307387, r307544, r307550, r318137, r319125, r319295

r306325 by marcel:
Replace the use of linker sets with constructors for both the
formats and schemes. Formats and schemes are registered at
runtime now, rather than collected at link time.

r306329 by marcel:
Eliminate the use of EDOOFUS. The error code was used to signal
programming errors, but is really a poor substitute for assert.
And less portable as well.

r306330 by marcel:
Avoid depending on the <sys/endian.h> header for le*enc and be*enc.
Not only is the header unportable, the encoding/decoding functions
are as well. Instead, duplicate the handful of small inlines we
need into a private header called endian.h.

Aside: an alternative approach is to move the encoding/decoding
functions to a separate system header. While the header is still
nonportable, such an approach would make it possible to re-use the
definitions by playing games with include paths. This may be the
preferred approach if more (build) utilities need this. This
change does not preclude that. In fact, it makes it easier.

r306333 by marcel:
Portability changes:
1. macOS nor Linux have MAP_NOCORE nor MAP_NOSYNC. Define as 0.
2. macOS doesn't have SEEK_DATA nor SEEK_HOLE. Define as -1
so that lseek will return -1 (with errno set to EINVAL).
3. gcc correctly warns that error is assigned but not used in
image_copyout_region(). Fix by returning on the first error.

r306620 by marcel:
Replace STAILQ with TAILQ. TAILQs are portable enough that they can
be used on both macOS and Linux. STAILQs are not. In particular,
STAILQ_LAST does not next on Linux. Since neither STAILQ_FOREACH_SAFE
nor TAILQ_FOREACH_SAFE exist on Linux, replace its use with a regular
TAILQ_FOREACH. The _SAFE variant was only used for having the next
pointer in a local variable.

r306621 by marcel:
Prefer <stdint.h> over <sys/types.h>. While here remove redundant
inclusion of <sys/queue.h>.

Move the inclusion of the disk partitioning headers out of order
and inbetween standard headers and local header. They will change
in a subsequent commit.

r306622 by marcel:
Replace OFF_MAX with INT64_MAX. The former is defined on Linux.

r307387 by marcel:
Switch to using the portable partition scheme headers.

r307544 by marcel:
o Provide a private definition for UUIDs (mkimg_uuid_t) because
UUIDs are not portable.
o Move mkimg_uuid() to a new file and merge both gpt_uuid_enc()
and vhd_uuid_enc() into a single mkimg_uuid_enc() that lives
in the same file.
o Move the OS-specific implementation of generating a UUID to
osdep_uuidgen() and provide the implementations for FreeBSD,
macOS and Linux.
o Expect the partitioning scheme headers to be found by having
a search to the directory in which the headers live. This
avoids conflicts on non-FreeBSD machines.

r307550 by imp:
Add a new flag to mkimg (-a num) to specify the active partition for
those partitioning schemes that have this concept. Implement it as an
override for mbr's setting 0x80 in the flags for the first partition
when we have boot code.

Differential Revision: https://reviews.freebsd.org/D4403

r318137:
mkimg: Add -C argument to specify maximum capacity

Add a -C option to specify a maximum capacity for the final image file.
It is useful to control the size of the generated image for sdcard or
when we will add dynamic size partition.

Add --capacity which is a shorthand to define min and max capacity at
the same time.

Reviewed by: bapt, marcel, wblock (manpages)
Sponsored by: Gandi.net
Differential Revision: https://reviews.freebsd.org/D10509

r319125:
mkimg: Correct an off by one error in the PMBR size

The PMBR last sector should be number of sector - 1 (As stated in UEFI Spec
2.6 page 118 table 17).
This fixes warning printed by linux tools like parted or fdisk.

Sponsored by: Gandi.net

r319295 by ngie:
Update the usr.bin/mkimg golden test output files after ^/head@r319125

^/head@r319125 changed the location of the backup pmbr, requiring the
output files to be regenerated, since they're binary disk dumps.

The output files were regenerated with "make rebase"--fixed in
^/head@r319294.

MFC with: r319125, r319294
PR: 219673
Sponsored by: Dell EMC Isilon

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Don't resize again prior to writing. Resizing may not be idempotent
and no scheme adjusts the size after the format resized the image
the first time.

MFuser/marcel/mkimg:
Add support for different output formats:
1. The output file that was previously written is now called the raw format.
2. Add the vmdk output format to create VMDK images.

When the format is not given, the raw output format is assumed.

Have the format resize twice. The first time is before we call
scheme_write(). The second time is immediately before we call
the format's write function. The first call is needed to have
the scheme know the right image size. The second call is needed
to compensate for the scheme adjusting the size while writing.

Give output formats a chance to (re-)size the image before the
scheme adds the partitioning metadata. This is needed by VMDK
to round the image size to the grain size.

Add format_write() that calls the write() function of the output
format. Have the raw format use image_copyout() for now.

Add a linker set for output formats. This is mostly copied and trimmed
from the linker set for schemes. Add stubs for raw and vmdk output
formats so as to demonstrate that the usage message is correct.