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

Add ZFS support to the bsdinstall partition editor and sade.

Submitted by: Kurt Lidl (original version)
MFC after: 6 weeks

After EFI support was added to the installer, it needed to allow boot
partitions of types other than "freebsd-boot" (in particular, "efi").
This allows the removal of some nasty hacks for supporting PowerPC systems,
in particular aliasing freebsd-boot to apple-boot on APM and an IBM-specific
code on MBR.

This changes the installer to use the correct names, which also breaks a
degeneracy in the meaning of "freebsd-boot" that allows the addition
of support for some newer IBM systems that can boot from GPT in addition to
MBR. Since I have no idea how to detect which those systems are, leave
the default on IBM PPC systems as MBR for now.

Add EFI support to the installer. This requires that the kernel provide
a sysctl to determine what firmware is in use. This sysctl does not exist
yet, so the following blocks are in front of the wheels:
- I've provisionally called this "hw.platform" after the equivalent thing
on PPC
- The logic to check the sysctl is short-circuited to always choose BIOS.
There's a comment in the top of the file about how to turn this off.

If IA64 acquired a boot1.efifat-like thing (probably with very few
modifications), the same code could be adapted there.

Add installer support for CHRP/PAPR PowerPC systems that use MBR+BSD
formatting, like x86, but with an additional MBR slice containing a raw
boot partition.

Approved by: re (gjb)

Experimental support for booting CHRP-type PowerPC systems from hard disks.

Add PS3 partitioning (and framework for future pseries support) to the
installer.

Import bsdinstall. This is meant to be (eventually in conjunction with
pc-sysinstall) a replacement for sysinstall in the 9.0 release and beyond.
Currently supported platforms are sparc64, pc98, i386, amd64, powerpc, and
powerpc64. Integration into the build system will occur in the coming
weeks.

Merging with pc-sysinstall will use this code as a frontend, while
temporarily retaining the interactive partition editor here. This work
will be done in parallel with improvements on this code and release
integration.

Thanks to all who have provided testing and comments!