[X86] Relocate code of replacement of subtarget unsupported masked memory...

[X86] Relocate code of replacement of subtarget unsupported masked memory intrinsics to run also on -O0 option.

Currently, when masked load, store, gather or scatter intrinsics are used, we check in CodeGenPrepare pass if the subtarget support these intrinsics, if not we replace them with scalar code - this is a functional transformation not an optimization (not optional).

CodeGenPrepare pass does not run when the optimization level is set to CodeGenOpt::None (-O0).

Functional transformation should run with all optimization levels, so here I created a new pass which runs on all optimization levels and does no more than this transformation.

Differential Revision: https://reviews.llvm.org/D32487

llvm-svn: 303050