Make -verify a -cc1 NoDriverOption

'%clang -verify' will now issue an error instead of succeeding without
verification. This should catch flawed tests like r199347.

Followup to r199451.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@199455 91177308-0d34-0410-b5e6-96231b3b80d8