CC1: Only parse command-line options that have the CC1Option flag.

We already reject flags that don't have the CC1Option flag,
but we would previously do so after parsing the command-line
arguments.

Since the option parser now has a parameter for excluding options,
we should just use that instead.

Differential Revision: http://llvm-reviews.chandlerc.com/D1270

llvm-svn: 187668