vaapi: Update for libva forwards compatibility

There was a downstream patch applied for protected content for libva.
This patch is now upstreamed, but is not compatible with the downstream
version. This change will allow us to update libva in ChromeOS to an
intermediate version that'll be compatible with both downstream and
upstream. Then we can shift Chrome to the upstream API, and then remove
the downstream compatibility layer from ChromeOS after that and be on
upstream.

BUG=b:174951211
TEST=Chrome builds, protected content plays back

Change-Id: Id06b21daf19a54b340236b354b5f4a828e2362de
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2672690


Reviewed-by: Andres Calderon Jaramillo <andrescj@chromium.org>
Reviewed-by: J Kardatzke <jkardatzke@chromium.org>
Commit-Queue: J Kardatzke <jkardatzke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#850949}