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

[Petr Hosek via llvm-commits]

petrhosek wrote:

> BTW, this is a recent development in gcc to support picolibc.
> 
> https://inbox.sourceware.org/gcc-patches/20260102000705.785004-1-keithp@keithp.com/
> 
> Posting this to not make the current discussion go tangential, but we are looking for a solution to select alternative libc's since LLVM is already part of the environment as per @quic-k / @michaelrj-google.
> 
> Can this patch be approved for merge ?

Is there an example of the Picolibc target triple for GCC? I looked for one but couldn't find it. In the GCC patch I noticed that Picolibc is selected for `*-picolibc-*` and not `*-*-picolibc` which would imply that `picolibc` is either a vendor or an OS component, but not an environment?

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