Try to fix the cl-options.c test on ARM bots

The test was failing because clang-cl changes the default triple
to target MSVC-style Win32. This is kind of wonky, but hasn't been
a problem until we started warning:

  warning: unknown platform, assuming -mfloat-abi=soft

Some of the tests in cl-options.c were running with -Werror, causing them
to fail.

Fixing this by FileCheck-ifying those tests instead of using -Werror.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@205049 91177308-0d34-0410-b5e6-96231b3b80d8