[clang] [flang] [llvm] [flang][cmake][perf-training] Optimize flang with PGO and BOLT (PR #197947)

[Paul Osmialowski via cfe-commits]

pawosm-arm wrote:

Update: I've added stage2-check-clang and stage2-check-flang targets, see issue #202072 for more details.

https://github.com/llvm/llvm-project/pull/197947