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

[Chris Apple via cfe-commits]

cjappl wrote:

So it's happening in a pass away from the Realtime sanitizer pass, the top of the stack says:

```
3.	Running pass 'Function Pass Manager' on module '/home/b/sanitizer-aarch64-linux-fuzzer/build/llvm-project/compiler-rt/lib/ubsan_minimal/ubsan_minimal_handlers.cpp'.
4.	Running pass 'AArch64 Instruction Selection' on function '@_ZL12decorate_msgPcm'
 #0 0x0000b8be034b8d04 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/b/sanitizer-aarch64-linux-fuzzer/build/llvm_build0/./bin/clang+++0x6118d04)
```

I'm not sure how this change would have affected the AArch64 Instruction Selection pass, still investigating.

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