[llvm] [libc][bazel] Create libc_release_library for release configurations. (PR #130694)

[Alexey Samsonov via llvm-commits]

vonosmas wrote:

> > > Is this something that could also be provided by a CMake cache file?
> > 
> > 
> > Joseph, could you elaborate? Do you suggest taking the list of sources/headers required to build a particular set of targets from the cache file CMake constructs? That probably wouldn't work in the Bazel world, where the CMake is never executed.
> 
> I just mean if we have special release configurations if that's something we should export through CMake as well.

Ah, OK. I would defer to @michaelrj-google  and @lntue  here, but I believe that CMake is somewhat ahead in terms of "release configuration" support? E.g. it has a concept and implementation of OS/arch-specific entrypoints and sets of headers under /libc/config. Up to this point, Bazel has no way of assembling a list of standalone libc functions into something like "library", this CL is a first small step towards doing that.

https://github.com/llvm/llvm-project/pull/130694