[clang] [Clang] Don't use crtbegin/crtend when building for musl. (PR #85089)

[Fangrui Song via cfe-commits]

https://github.com/MaskRay requested changes to this pull request.

Thanks for working on musl but I don't think this is correct.
A musl-cross-make build does use crtbegin/crtend, though technically the files can be empty.

https://github.com/llvm/llvm-project/pull/85089