Pull in r215811 from upstream llvm trunk (by Nico Weber):

  arm asm: Let .fpu enable instructions, PR20447.

  I'm not very happy with duplicating the fpu->feature mapping in ARMAsmParser.cpp
  and in clang's driver. See the bug for a patch that doesn't do that, and the
  review thread [1] for why this duplication exists.

  1: http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20140811/231052.html

This makes the .fpu directive work properly, so we can successfully
assemble several .S files using the directive, under lib/libc/arm.
Add patch file for r275280.