Merge branch 'devs/devilhorns/wip'

This push merges some changes to the evas wayland shm engine. These
changes help to reduce dropped frames, fix max buffer age, provide
a better next buffer selection algorithm, and move buffer flipping out
of the render thread. In total, these provide better wayland_shm
engine performance. These patches are based on previous drm engine work
by Derek Foreman.