[clang] [clang][rtsan] Introduce realtime sanitizer codegen and driver (PR #102622)

[Chris Apple via cfe-commits]

cjappl wrote:

(investigating this issue right now, I'm unfamiliar with the fuzzer, so I'm trying to figure out if this is my failure or not. Will keep people posted)

https://github.com/llvm/llvm-project/pull/102622