Make a separate dirty bit DIRTY_ATTRIB_POINTER_BUFFER for vertex
attrib's binding buffer change. So in handling glVertexAttribPointer,
ANGLE will only modify a vulkan graphics pipeline when attrib.format,
attrib.stride or attrib.divisor change. If only the VBO pointer changes,
then Vulkan can update the state via "vkCmdBindVertexBuffers()" without
triggering a pipeline update.
Bug: angleproject:3256
Change-Id: I01e02adde3708963b496a20050a5723e8eb57ab2
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1707614Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jiacheng Lu <lujc@google.com>
