Fill out our support for the floating-point status and control register
instructions (mcrfs and friends). As it turns out, these are necessary for
compiling src/test/harness_fp.h in TBB for PowerPC.
Thanks to Raf Schietekat for reporting the issue!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226070 91177308-0d34-0410-b5e6-96231b3b80d8