[compiler-rt] Reland HIP offload PGO runtime support as a separate opt-in library (PR #201606)

[Yaxun Liu via llvm-commits]

yxsamliu wrote:

This is the compiler-rt half of the offload PGO reland. The compiler-side change (instrumentation, codegen, and the driver wiring that links clang_rt.profile_rocm) is in #201607 and depends on this one.

https://github.com/llvm/llvm-project/pull/201606