[compiler-rt] [rtsan][compiler-rt] Introduce __rtsan_notify_blocking_call (PR #109529)

[via llvm-commits]

davidtrevelyan wrote:

Thanks everyone for the valuable input, I've drafted a PR for removing the `std::variant` in rtsan here: https://github.com/llvm/llvm-project/pull/109786

https://github.com/llvm/llvm-project/pull/109529