[X86] Teach getSetCCResultType to handle more than just SimpleVTs when looking...

[X86] Teach getSetCCResultType to handle more than just SimpleVTs when looking at larger than 512-bit vectors.

Which VTs are considered simple is determined by the superset of the legal types of all targets in LLVM. If we're looking at VTs that are going to be split down to 512-bits we should allow any VT not just simple ones since the simple list changes over time as new targets are added.

llvm-svn: 319110