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

[via cfe-commits]

dankm wrote:

You do bring up an interesting point, though. When linking C code with this change, for both Gnu and FreeBSD, `-stdlib=libbad` is ignored for C and raises an error for C++.

Also for reference, the toolchains that ignore the stdlib argument for C are: baremetal, Darwin, Fuchsia, Gnu, Hexagon, MipsLinux, NaCL, OHOS, and WebAssembly. I was mistaken above about Darwin.

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