[compiler-rt] [Sanitizers] Remove freebsd/netbsd from "posix" file (PR #123269)

[Kyle Lippincott via llvm-commits]

spectral54 wrote:

I don't have access to select reviewers, but @thurstond mentioned that I could add them as a reviewer. 

This is patch 1 of 6 in a series. I couldn't get graphite to work (I think because I'm not part of the llvm organization?), so I was just going to send them manually, with the next one being sent after the previous one lands. The entire series can be seen here: https://github.com/llvm/llvm-project/compare/main...spectral54:llvm-project:users/spectral/regexec-06-implement-startend

I intentionally didn't run clang-format on this commit, because it introduces a LOT of changes to this file and I didn't think that was correct.

https://github.com/llvm/llvm-project/pull/123269