Vulkan: Add OpenGL line segment rasterization. Line rasterization rules are implemented using a shader patch. The patch does a small test and discards pixels that are outside of the OpenGL line region. The feature is disabled on Android until we can determine the root cause of the test failures. Bug: angleproject:2598 Change-Id: Ic76c5e40fa3ceff7643e735e66f5a9050240c80b Reviewed-on: https://chromium-review.googlesource.com/1120153 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>