[clang-tools-extra] [clang] [compiler-rt] [PGO] Reland PGO's Counter Reset and File Dumping APIs #76471 (PR #78285)

[Qiongsi Wu via cfe-commits]

qiongsiwu wrote:

@w2yehia I think a reasonable way to go forward is to remove the testing of `__llvm_orderfile_dump` from the main test, and add a separate test that runs only on Darwin. 

What do you think? 

https://github.com/llvm/llvm-project/pull/78285