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

[Michael Jones via llvm-commits]

michaelrj-google wrote:

I don't think we currently have a way for CMake to build all of the library targets as one massive library, right now it's all individual targets that get combined into a `libc.a`. I'm not opposed to adding this functionality to cmake, but it'd need more than just a cmake cache file. Adding something like this would involve adding a bunch of new cmake to collect all the non-skipped targets' sources, and also creating a new target for the monobuild library.

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