Write relative paths with forward slashes to the code generation hashes. This should avoid generating diffs when running the code generation with different source directories or on different platforms. BUG=angleproject:2695 Change-Id: I67776883bdbeb867a49bea00f16998c04f7857b4 Reviewed-on: https://chromium-review.googlesource.com/1127355 Commit-Queue: Geoff Lang <geofflang@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>