MFC r325834,r325997,326502: Move sys/boot to stand/

This is effectively a direct commit to stable/11, due to differences between
stable/11 and head. Changes to DTS in sys/boot/fdt/dts were often
accompanied by kernel changes. Many of these were also risc-v updates that
likely had many more dependencies to MFC.

Because of this, sys/boot/fdt/dts remains as-is while everything else in
sys/boot relocates to stand/.

r325834: Move sys/boot to stand. Fix all references to new location

r325997: Remove empty directories.

r326502: Document the sys/boot -> stand move in hier.7 and the top-level README.

MFC r324551: Move lib/libstand to sys/boot/libsa

MFC Loader Fixes 2017q2: r316437,r316577,r316578,r316585,r316590,r316612,
r316625,r316628,r316654,r316682,r316704,r316771,r317092,r317097,r317099,
r317652,r317785,r317886,r317887,r318142,r318320,r318356,r318678,r318754,
r318982,r318986,r318987,r318988,r318989,r318990,r318991,r318992,r318993,
r318994,r318999,r319083,r319084,r319085,r320011,r320234,r320288,r320304,
r320467,r320482

r316437: Small cleanup to make i386/loader match efi/loader boot environment
code

r316577: loader: part.c cstyle cleanup

r316578: loader: want mechanism to avoid RA with bcache

r316585: loader: zfs reader should check all labels

r316590: libstand/dosfs: cache FAT32 in 128 Kb blocks to save loader memory

r316612: In r298230 the value of HEAP_MIN was changed from 3MB to 64MB.
Correct a comment.

r316625: Do not use -msoft-float with intention of disabling FP on aarch64

r316628: Silence GCC warning by initializing the local variable.

r316654: loader: r316585 did miss userboot update

r316682: loader: r316585 did miss sparc/ofw

r316704: loader.efi: only fetch zfs pool guid for the actual boot device

r316771: loader: Avoid possible overflow via environment variable

r317092: loader: zfs reader vdev_probe should check for minimum device size

r317097: loader: F_READ/F_WRITE should be checked against masked flag

r317099: loader: uboot disk ioctl should call disk_ioctl

r317652: loader.efi: ResetSystem does not use data with EFI_SUCCESS

r317785: zfsboot: drvsize() may be unusable on some systems

r317886: distinguish NFS versus TFTP boot by rootpath

r317887: loader: network read rework

r318142: libstand: NULL pointer dereference in rarp

r318320: loader: add ip layer code into libstand

r318356: libstand: increase nfs max read size to 16k

r318678: Replacing iterating over rootpath by strsep(3).

r318754: Pass -N directly to ld via -Wl rather than passing it to the
compiler driver.

r318982: Pass a "FREEBSD" user-class in PXE dhcp request

r318986: add a comment on vendor index 19 and 20 to avoid confusion

r318987: Support URI scheme for root-path in netbooting

r318988: Always build tftpfs support along with nfs for pxeboot

r318989: Always issue the pxe request

r318990: Partially revert r314948

r318991: Document recent changes on pxeboot

r318992: Capitalize DHCP

r318993: Use the usual FreeBSD spelling for the DHCP user class

r318994: Catch with the change in the user class

r318999: Update the comments concerning net_parse_rootpath to reflect what
it is now

r319083: Followup on the user-class changes

r319084: Small cleanup in dev_net.c

r319085: use the same option list for dhcp discovery and request

r320011: Add chain loader support for loader

r320234: Make structure padding explicit in EFI_MEMORY_DESCRIPTOR

r320288: Allow Clang's integrated assembler to assemble boot0

r320304: loader.efi: Disable smbios for arm

r320467: loader: chain load relocate data declaration is bad

r320482: As with arm64 mark the EFI PE header as allocated on arm.

PR: 218473

MFC: 304677, 304680, 305125, 305770, 305769

r304677:
Add tftpfs support for the EFI loader

Allow netbooting on efi without having to setup any NFS server by rebuilding the
loader with LOADER_TFTP_SUPPORT like for the i386 pxeloader

r305125:
Netboot: allow both tftpfs and nfs in both pxeboot and loader.efi

Add a new 'netproto' variable which can be set for now to
NET_TFTP or NET_NFS (default to NET_NONE)

From the dhcp options if one sets the root-path option to:
"ip:path", the loader will consider it is booting over NFS
(meaning same behaviour as the default current behaviour)

if the dhcp option "tftp server address" is set (option 150)
the loader will consider it is booting over tftpfs, it will then
consider the root-path options with 2 possible case
1. "path" then the IP of the tftp server will be the one passed by
the option 150, and the files will be retrieved under "path" on the tftp
server
2. "ip:path" then the IP of the tftp server will be the one passed in
the option "overwritting the IP from the option 150.

We could not "abuse" the rootpath option in the form or tftp://ip:path because
this is already used for other purpose by iPXE preventing any chainload from
iPXE to the FreeBSD loader.

Given at each open(), the loader loops over all available filesystems and keep
the "best" error, we needed to prevent tftpfs to fallback on nfs and vice versa.
the tftpfs and nfs implementation in libstand now return EINVAL early if
'netproto' for that purpose.

Relnotes: yes
Sponsored by: Gandi.net

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

Correct comment.

MFC after: 2 weeks

If the dhcp server delivers an interface-mtu option, parse it and store
the value in a new global intf_mtu for use by the application.

These changes were inspired by the patch provided by Robert Blayzor in
PR 187094, and will allow loader(8) to propagate the value to the kernel
along with the other nfs_diskless parms delivered via environment vars.

Add __FBSDID()s to libstand

This commit was generated by cvs2svn to compensate for changes in r38451,
which included commits to RCS files with non-trunk default branches.

This is libstand; a support library for standalone executables (eg. bootstrap
modules).
Obtained from: NetBSD, with some architectural changes and many additions.