Revert "try to fix windows build after 73e585e4" and

Revert "Reland "[lld/coff] Make lld-link work in a non-MSVC shell, add /winsysroot:""

This reverts commit 0574b5fc and 73e585e4.

This change is causing the test Driver/cl-options.c to fail on Windows buildbots.
https://lab.llvm.org/staging/#/builders/204/builds/1343