[clang] [Driver] Silence stdlib warning when linking C on FreeBSD (PR #68011)

[Egor Zhdan via cfe-commits]

https://github.com/egorzhdan approved this pull request.

The Darwin toolchain also does this. This change LGTM, although I'm not an expert in FreeBSD.

https://github.com/llvm/llvm-project/pull/68011