[clang] [compiler-rt] Rtsan fbsd (PR #125389)

[Chris Apple via cfe-commits]

cjappl wrote:

> @devnexen in principle, I'm of course not opposed to rtsan supporting FreeBSD - is there any motivation in particular for why you propose adding it here? Is this the first of many patches that are needed, or is it the only one that you can foresee? I'd like to make sure that the maintenance overhead will be worth it going forwards.
> 
> @cjappl have you got any concerns with introducing FreeBSD support?

I have no specific concerns, but I agree we should be sure any maintenance cost is worth enabling it. Maybe we can keep this PR open and see if it attracts any comments by people wanting it?

I don't think we should enable it just to enable it. We have had strong signals of support on MacOS, Linux and (not implemented) Windows. We have not had any feedback asking for support on the BSD flavors yet.

https://github.com/llvm/llvm-project/pull/125389