[AIX] do not emit visibility attribute into IR when there is -mignore-xcoff-visibility

SUMMARY:

n the patch https://reviews.llvm.org/D87451 "add new option -mignore-xcoff-visibility"
we did as "The option -mignore-xcoff-visibility has no effect on visibility attribute when compile with -emit-llvm option to generated LLVM IR."

in these patch we let -mignore-xcoff-visibility effect on generating IR too. the new feature only work on AIX OS

Reviewer: Jason Liu,

Differential Revision: https://reviews.llvm.org/D89986