Driver: Skip the -fmodules-cache-path argument in driver crash diags

The modules cache path shouldn't be included in crash reports, as it's
a system (or run) specific directory.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@206922 91177308-0d34-0410-b5e6-96231b3b80d8