[clang] [flang] [llvm] [flang-rt] Pass the whole path of libflang_rt.runtime.a to linker on AIX (PR #131041)

[Daniel Chen via llvm-commits]

DanielCChen wrote:

Hello reviewers,
I have rebased the PR to pull the change of enabling `PER_TARGET_RUNTIME_DIR` on AIX in.
I also added a couple of LIT tests to test the flang-rt path on both AIX and LoP.

Thanks for your time reviewing the PR!

https://github.com/llvm/llvm-project/pull/131041