MFC r326276:

various: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

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

- Simplify code by using g_*() API.
- Don't use u_char and u_int in userland.
- Change 'unsigned' to 'unsigned int'.
- Update copyright years.

MFC after: 1 week

Remove G_TYPE_ASCLBA type and replace it with G_TYPE_STRING in gpart.
Move code that converts params from humanized numbers to sectors count
to subr.c and adjust comment.
Add post-processing for "size" and "start offset" params in gpart,
now they are properly converted to sectors count with known sector size
that can be greater that 512 bytes.
Also replace "unsigned long long" type to "off_t" for unify code since
it used for medium size in libgeom(3) and DIOCGMEDIASIZE ioctl.

PR: bin/146277
Reviewed by: marcel (previous version)
Approved by: kib (mentor)
MFC after: 1 month

Add two support functions:
o gctl_delete_param() -- intended for parameters that are consumed
by geom(8) itself and which should not be passed to the kernel.
o gctl_has_param() -- intended to check if optional parameters are
present.

Both are needed by gpart(8) to process the optional parameter for
writing bootcode to a partition (as part of the bootcode verb).
However, the kernel is itself not involved in this matter and the
parameter needs to be removed from the request destined for the
kernel.

Implement gctl_change_param() function, which changes value of existing
parameter.

MFC after: 1 week

Add __printflike() attribute to various functions.

Remove trailing spaces.

- The geom(8) utility only uses three types of arguments: string (char *),
value (intmax_t) and boolean (int).
Based on that provide three functions:
- gctl_get_ascii()
- gctl_get_int()
- gctl_get_intmax()
- Hide gctl_get_param() function, as it is only used internally in
subr.c.
- Allow to provide argument name as (fmt, ...).
- Assert geom(8) bugs (missing argument is a geom(8) bug).

- Clean-up and simplify the code by using new functions and assumtions
(no more checking for missing argument).

Tested by: regression tests

Move function for calculating number of bits into more central place.
I want to use it so more.

MFC after: 3 days

MFp4: gmirror(8) is coming soon, and we need g_metadata_read() there.

Implement 3 new functions:
- g_lcm() - calculates Least Common Multiple of two given values,
it is helpful when we need to find sector size for provider
which is based on disks with different sector size;
- g_get_mediasize() - returns media size of given provider;
- g_get_sectorsize() - returns sector size of given provider;
Those function aren't used now, but are used by geom_mirror which will be
committed soon.

Bring in geom(8) utility. It is an universal utility for operating on
GEOM classes. It works by loading a shared library via dlopen(3) mechanism
with class-specific code, it is also responsible for communicating with
GEOM via libgeom(3).
Per-class shared libraries are going to be stored in /lib/geom/ directory.
It provides also few standard commands like 'list', 'load' and 'unload'
for existing classes which aren't aware of geom(8).
More info will be send on freebsd-current@ mailing list.

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