Rolling Vulkan validation code forward to HEAD of master as of 4/16/18
morning. Disable Vulkan from the ANGLE build until ANGLE lands in
Chromium. After that second part of roll will be submitted.

This LVL update includes MockICD fixes to allow ANGLE perf tests to
run correctly with Null Vulkan configuration.

Bug: angleproject:2482
Change-Id: I61dc9ed293677a1b5839b605d7c3640dca138db3
Reviewed-on: https://chromium-review.googlesource.com/1014405Reviewed-by: Jamie Madill <jmadill@chromium.org>