Auto merge of #121426 - madsmtm:remove-cc-syslibroot, r=pnkfelix

Remove redundant `-Wl,-syslibroot`

Since `-isysroot` is set, [Clang already passes this when invoking the linker](https://github.com/llvm/llvm-project/blob/llvmorg-17.0.6/clang/lib/Driver/ToolChains/Darwin.cpp#L439-L442).

See rust-lang/rust#56833 for when the `-isysroot` was originally added, but didn't remove the unnecessary linker flag.

CC `@BlackHoleFox`
r? shepmaster