[PATCH] Move VFP4 predicate inside UseFusedMAC

[Tim Northover]

Hi Daniel,

> UseFusedMAC will only be true if VFP4 is available, correct?

UseFusedMAC is a Predicate affecting CodeGen, not assembly. For
example the Darwin assembler will still accept vfma even though LLVM
won't use it. HasVFP4 is (also) a subclass of AssemblerPredicate, tied
to particular CPUs and *does* get used by the assembler.

Basically, UseFusedMAC isn't being checked by the assembler and it
would give incorrect results even if it was.

Cheers.

Tim.