Correct case for includes. This is needed for building on MinGW. Bug: angleproject:3330 Change-Id: I4a7e7d6f6e14be7e1ba67d3ceb45b11d00585119 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1544749 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>