[llvm] [Clang] Add Picolibc environment type for triples (PR #169613)

[Peter Smith via llvm-commits]

smithp35 wrote:

> any idea who else we can add here to reach this consensus?

I think it would be sufficient to cover the people on this review already. Perhaps add Michael Jones michaelrj-google as the LLVM libc lead. Would be useful to add a link from the Discourse post https://discourse.llvm.org/t/rfc-add-command-line-option-for-selecting-c-library/87335/22 too.

I'm fine with the discussion to be had here if I'm the only one that cares about it. I'm OK with adding picolibc with the expectation that llvmlibc, newlib and possibly newlib-nano may follow.

https://github.com/llvm/llvm-project/pull/169613