previously collected info from the .file directives and outputs the encoded
bytes for it. For now this is only in the Mach-O streamer but at some point
will move to a more generic place.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110617 91177308-0d34-0410-b5e6-96231b3b80d8