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

[Chris Apple via cfe-commits]

cjappl wrote:

At least 3 more failures in this way since this reversion:
https://lab.llvm.org/buildbot/#/builders/159/builds/4477
https://lab.llvm.org/buildbot/#/builders/159/builds/4478
https://lab.llvm.org/buildbot/#/builders/159/builds/4479


I am going to re-land this tomorrow when I wake up

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