Add a test for --reproduce on Windows.

It is insanely hard to write a test that works both on Windows and Unix.
I tried to workaround it with cpio's minor options, but the behaviors of
the options were myterious. It just doesn't worth to spend time on it.
And probably minor options could break buildbots that doesn't have the
GNU version of cpio command.

In this patch, I simply added a separate test file that runs only on
Windows.

llvm-svn: 268596