COFF: Don't add /manifest* flags to the response file.

If /manifest:embed is enabled we're already creating a resource file
out of these flags and adding it to the linkrepro, and it doesn't
seem worth being able to repro side-by-side manifests.

Includes a test that covers this commit as well as r315948.

Differential Revision: https://reviews.llvm.org/D38975

llvm-svn: 316547