[LLD][COFF] Fix /linkrepro with output options that take a filename or path

The following options: /pdb, /out or /implib now emit in the repro.tar/response.txt only a filename stripped from its path, to avoid non-existent paths on the reproducer's machine.

Differential Revision: https://reviews.llvm.org/D59530

llvm-svn: 358980