This will allow us to move common headers, such as extension headers, to
common/vulkan.

Bug: b/159027603
Bug: b/154620295
Change-Id: I1ff73dc5b7ee8f7dfb3ac0c5f30bd4b3a8183aeb
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2248205
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Tim Van Patten <timvp@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>