RFR: Convert path separators in patch file to unix explicitly

[JornVernee via github.com]

I ran into trouble when trying to apply a patch file generated with Windows Git to a mercurial repository through cygwin. It wasn't recognizing the files since the paths in the patch file were using Windows path separators.

The spec doesn't seem to mention path separators: https://www.gnu.org/software/diffutils/manual/html_node/Detailed-Unified.html#Detailed-Unified

But, both the Windows Git and Mercurial clients I have installed are handling unix path separators just fine. So, in this PR I've changed the patch file generators to use unix path separators explicitly, which solves the problem.

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Commits:
 - cefd6ae1:	Convert path separators in patch file to unix explicitly

Pull request:
http://git.openjdk.java.net/skara/pull/35

Webrev:
https://openjdk.github.io/cr/skara/35/webrev.00

Patch:
http://git.openjdk.java.net/skara/pull/35.diff

Fetch command:
git fetch https://github.com/openjdk/skara.git pull/35/head:pull/35