vp9: Add nonref frame buffer test.

The new test will run a SVC bitstream which has non ref frames.
It checks the number of buffer acquired and released to make sure all
external frame buffers are released.

Add a new test bitstream:
vp90-2-22-svc_1280x720_1.webm
which has 400 frames in total, and 1 spatial layer and 2 temporal layers.
There is one non ref frame every other frame.

Disabled for now. Will be enabled with the fix.

BUG=b/68819248

Change-Id: I0515336fd9809a9e1fceba90e4dce53dabaf53a5
4 files changed