[clang] [flang] [llvm] Fix and reapply IR PGO support for Flang (PR #142892)

[Tarun Prabhu via cfe-commits]

tarunprabhu wrote:

Thanks for the fix @kiranchandramohan. I didn't spot the issue with `llvm-profdata`

https://github.com/llvm/llvm-project/pull/142892