We use new logic to compare if the attribute format changes before
setting dirty bits. This improves performance of VBO-only state changes
significantly. On the VBO change Vulkan microbenchmark gives about a
30% improvement.

Bug: angleproject:3256
Change-Id: Ifaf1c92ed7a09422156ef79b5983e7349de63346
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1684294Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>