clang-cl: Ignore the new /Zo[-] option (PR21571)

Also fix the ignored options test which didn't fail properly on
unknown options.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@222013 91177308-0d34-0410-b5e6-96231b3b80d8
Typo fix.



git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@222016 91177308-0d34-0410-b5e6-96231b3b80d8