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

[Volodymyr Turanskyy via llvm-commits]

voltur01 wrote:

Thank you for referring to the RFC! We are still interested in having an option like that in Arm Toolchain for Embedded since we support multiple libraries and need a clean way of selecting the one to use, however we did not have to start the implementation yet.

Happy to do the reviews, if anyone has the bandwidth to start working on such a command line option sooner than us.

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