[clang] [Clang][Driver] Revise Cygwin ToolChain to call linker directly (PR #147960)

[Tomohiro Kashiwada via cfe-commits]

kikairoya wrote:

If we should consider cross-compiling, it's needed to be aware that `$SYSROOT/usr/lib` doesn't appear in real filesystem.

https://github.com/llvm/llvm-project/pull/147960