Add new PowerPC relocations to binutils

Summary:
LLVM/Clang generates relocations that our binutils doesn't understand, but newer
binutils does.  I got permission from the author of a series of patches to
relicense them as GPLv2 for use in FreeBSD.  The upstream git hashes are:

ac2df442ac7901f00af15b272fc48b594b433713
2b95367962dc14f69d3c338c4d54195266e2e169
102890f04c44b64cf5cef4588267dd9f24086ac7
b7fcf6f6bb53b5027e111107f5416769cb9a5798
1d483afedd5a628dc84fb58d1d570f79fdfbfa7b
90aecf7a80c1cefeb45fc10a6cd02c8338e34b4c
3a71aa26df2a372a58e9c11ef9ba51fd0e83320a
727fc41e077139570ea8b8ddfd6c546b2a55627c

With the import of clang 3.5, and a few backported patches, we should be able to
move powerpc and powerpc64 to clang-as-cc soon.

Test Plan: Passes make tinderbox, so no regressions.  Binaries built with clang
run on powerpc64.

Reviewers: #committers, dim

Reviewed By: dim

Differential Revision: https://reviews.freebsd.org/D1297

Obtained from:	Alan Modra, upstream binutils-gdb git
MFC after:	3 weeks
Relnotes:	yes