+ Include fixed validation logic for GL_UNPACK_SKIP_IMAGES and GL_UNPACK_ROW_LENGTH
+ Include fix for Clang build break

BUG=angleproject:1186

Change-Id: I403a066e29614f532db6931755265d2ee088d442
Reviewed-on: https://chromium-review.googlesource.com/308746Tested-by: Austin Kinross <aukinros@microsoft.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>