dav1d: limit the number of extra frames needed by the decoder
The i_extra_picture_buffers
is used to add pictures to the pool that the core
will allocate. dav1d is actually using n_threads
frames. And the core is
allocating 10 frames per default for AV1. So we need to add the missing ones.
This is done only for dav1d 1.0. Older dav1d may have needed more frames so we leave the code untouched.
v3: update dav1d to make use of the new API to get this value properly, when it's available
Edited by Steve Lhomme