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.
llvm-mc: error when -compress-debug-sections is requested and zlib is not linked

This is a bit of a stab in the dark, since I have zlib on my machine.
Just going to bounce it off the bots & see if it sticks.

Do we have some convention for negative REQUIRES: checks? Or do I just
need to add a feature like I've done here?