[compiler-rt] [compiler-rt][rtsan] Use Die instead of exit, define cf.exitcode (PR #107635)

[Florian Mayer via llvm-commits]

fmayer wrote:

> A note on the error code. It must be < 255 on mac at least

just FYI, on Linux, I would make it < 128 (which you do) to not get into the signal exit codes.

https://github.com/llvm/llvm-project/pull/107635