Merging r245907:

------------------------------------------------------------------------
r245907 | hfinkel | 2015-08-24 19:48:28 -0400 (Mon, 24 Aug 2015) | 6 lines

[PowerPC] PPCVSXFMAMutate should ignore trivial-copy addends

We might end up with a trivial copy as the addend, and if so, we should ignore
the corresponding FMA instruction. The trivial copy can be coalesced away later,
so there's nothing to do here. We should not, however, assert. Fixes PR24544.

------------------------------------------------------------------------

llvm-svn: 252476