Julian Scheel authored Jan 19, 2015 and Rémi Denis-Courmont committed Jan 20, 2015

The mutex held within mmal_pictures is used to lock access of mmal
picture/buffer pools between vlc main thread and mmal callback threads. This
is only required to be locked per pool and not globally for all mmal modules.
Thus using a global mutex caused a slight performance hit when using mmal vout
and deinterlace simultaneously which operate on independent picture pools. Now
the pool owner provides the mutex handle when allocating the pictures, so
that independent locking can be used.

Signed-off-by: Julian Scheel <julian@jusst.de>
Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>