...which does not behave as expected with the given command line arguments, so
just strip "-cl.exe" (and any hard-coded command line arguments following it in
$CC, but that's probably rather harmless here).  Expects that clang-cl is given
with an ".exe" extension in $CC (not assuming that and stripping "-cl" and
everything that might follow could be a bit too agressive).

Change-Id: If99f964dda1369b7d4bbb63b3d634b93c9f935a8