Peephole optimization of ptest-conditioned branch in X86 arch. Performs...

Peephole optimization of ptest-conditioned branch in X86 arch. Performs instruction combining of sequences generated by ptestz/ptestc intrinsics to ptest+jcc pair for SSE and AVX.

Testing: passed 'make check' including LIT tests for all sequences being handled (both SSE and AVX)

Reviewers: Evan Cheng, David Blaikie, Bruno Lopes, Elena Demikhovsky, Chad Rosier, Anton Korobeynikov
llvm-svn: 147601