[X86] Improve optimizeCompareInstr for signed comparisons after BMI/TBM instructions

We previously couldn't optimize out a TEST if the branch/setcc/cmov
used the overflow flag. This patches allows the TEST to be removed
if the flag producing instruction is known to clear the OF flag.
Thats what the TEST instruction would have done so that should be
equivalent.

Need to add test cases. I'll try to get back to this if I have bandwidth.

Fixes PR48768.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D94856