Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

Regularize the Netflix copyright

Use recent best practices for Copyright form at the top of
the license:
1. Remove all the All Rights Reserved clauses on our stuff. Where we
piggybacked others, use a separate line to make things clear.
2. Use "Netflix, Inc." everywhere.
3. Use a single line for the copyright for grep friendliness.
4. Use date ranges in all places for our stuff.

Approved by: Netflix Legal (who gave me the form), adrian@ (pmc files)

libefivar: use standard 2-Clause FreeBSD license

Approved by: imp
Sponsored by: The FreeBSD Foundation

Simplify the efivar interface a little.

We started out having Linux compatible libefivar interfaces. This was
in anticipation of porting the GPL'd efibootmgr to FreeBSD via a
port. However, since we need that functionality in the base, that port
isn't going to happened. It also appears that efivar is a private
library that's not used much outside a command line util and
efibootmgr. Reduce compatibility with the Linux version a little by
removing the mode parameter to efi_set_variable (which was unused on
FreeBSD, and not set to something useful in the code we'd
written). Also remove some efi error routines that were never
implemented and existed only to placate early GPL efibootmgr porting
experiments.

Suggested by: Matt Williams
Sponsored by: Netflix

Minor fixes to edge cases in efi_get_next_variable_name

Fix allocating more memory for the names (unlikely to be needed, but
still best to get right) to ask for the length the kernel told use we
needed, not the old length of the variable. Mind the proper NUL that
we add in the space we allocate. Free the old name string before we
allcoate a new one to limit what we leak to the last one (free passed
in name for the last one in the list), and detect the last one by rv
!= 0 and errno == ENOENT, rather then just the former to avoid false
positives if errno happens to be ENOENT on entry.

Sponsored by: Netflix

Share UCS2/UTF8 routines between boot loader and userland.

Move the UCS2 to UTF8 routines over into sys/boot/efi and have
libefivar grab them from there.

Sponsored by: Netflix

Make sure guid table is compiled before we use it.

Sponsored by: Netflix

Only compile the known uuid table once.

Sponsored by: Netflix

Move uuid_table definition to efivar.h.
Create new function efi_known_guid() to return list of guids.

Sponsored by: Netflix

Don't convert ENOENT to nothing for individual lookup, just for the
iterative get_next interface. This prevents efivar(3) from printing 4k
of 0's when a variable isn't set.

Sponsored by: Netflix

Fix building on i386 and arm. But 'public domain' headers on the files
with no creative content. Include "lost" changes from git:
o Use /dev/efi instead of /dev/efidev
o Remove redundant NULL checks.

Submitted by: kib@, dim@, zbb@, emaste@

Create libefivar library. This library aims to provide
the same API as the GPL'd version of this library. It implements the common
Linux API for programatically manipulating UEFI environment varibales using
the UEFI Runtime Services the kernel provides. It replaces the old efi
library since it is programmed to a different interface, but retails the
CHAR16 to UTF-8 and vice versa conversion routines. The new name is to match
Linux program's expectations.

Differential Revision: https://reviews.freebsd.org/D8128
Reviewed by: kib@, wblock@, Ganael Laplanche