clang-cl: Allow /Fo without an argument (PR21589)

When it's used without an argument, the default file name is
used. The same goes for /Fe.

Also, allow using /Fo, /Fa and /Fe with multiple inputs if they
don't have an argument.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@222164 91177308-0d34-0410-b5e6-96231b3b80d8
Missing comma in a string array initialization (CID 1254893)

Summary:
We have this error from a while (Wed Jun 15 18:02:42 2011
r133103)

Reviewers: rsmith

Reviewed By: rsmith

Differential Revision: http://reviews.llvm.org/D6296

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@222169 91177308-0d34-0410-b5e6-96231b3b80d8