[clang] [flang] [llvm] Add IR Profile-Guided Optimization (IR PGO) support to the Flang compiler (PR #136098)

[Tarun Prabhu via cfe-commits]

https://github.com/tarunprabhu approved this pull request.

@fanju110, Thanks for seeing this through!

https://github.com/llvm/llvm-project/pull/136098