[clang] [SystemZ][z/OS] This change adds support for the PPA2 section in zOS (PR #65407)

[Yusra Syeda via cfe-commits]

ysyeda wrote:

Breaking this PR into 2 for chrono.h/.cpp changes and for zOS specific changes. 
The PR for UTC clock support is here: https://github.com/llvm/llvm-project/pull/65407

https://github.com/llvm/llvm-project/pull/65407