This commit uses the video-src-alloc and video-play-reneg templates to create
examples for manual fixation at the format negotiation phase. These
clients simulate modifier negotiation done by clients handling DmaBufs.
Note: Neither client is capable of proper DmaBuf handling!
video-play-fixate can be used to test if a producer is capable to
fallback to shm buffer transport, while video-src-fixate can only be
used with the former example!
