[lld] r268404 - Produce cpio files for --reproduce.

[Rafael Espíndola via llvm-commits]

> Chromium was using a zip file of gnuwin32 tools to run the tests, and it
> didn't have it. We just added it. I'm just... not sure it'll be present in
> every MSys installation under the sun.

Interesting. I did check that gnuwin32 had cpio. The file was trimmed?

The only test that runs cpio on windowsis reproduce-windows.s. I added
it to make sue we can create the reproducible on windows.

I guess I could just run grep on the cpio archive if running cpio on
windows is an issue.

Cheers,
Rafael