gnome: remove semaphore timed operation in video renderer.

The sem_timedwait() is replaced by a sem_trywait().
This patch seems also to resolve other --timeout-- bugs seen in the daemon.

This code is run by the main GUI event loop,
so never do locking stuff into it.

Change-Id: I4b68e6ec4527f67728a509701f5076c81dc35148