[clang] [clang][Driver][test] Fix Driver/solaris-ld.c on non-Unix hosts (PR #138466)

[Rainer Orth via cfe-commits]

rorth wrote:

> It's not due to non-Unix hosts. It's likely due to these builds setting CLANG_DEFAULT_RTLIB and CLANG_DEFAULT_UNWINDLIB.

That occured to me shortly after I created the PR.  I'll fix the description accordingly.

https://github.com/llvm/llvm-project/pull/138466