[AIX][XCOFF] Supporting the ReadOnlyWithRel SectionKnd

SUMMARY:
In this patch we put the global variable in a Csect which's SectionKind is "ReadOnlyWithRel" into Data Section.

Reviewers: hubert.reinterpretcast,jasonliu,Xiangling_L
Subscribers: wuzish, nemanjai, hiraditya

Differential Revision: https://reviews.llvm.org/D72461