xbmc/xbmc — pull request #3749 by popcornmix (2013-12-01 20:46:17+00:00)
Title: [rbp/omxplayer] Avoid segfault when switching fullscreen

Switching fullscreen causes a brief UnregisterAudioCallback/RegsisterAudioCallback.
If this occurs while audio thread is inside VizPacket then we segfault on dereferencing m_pCallback.

Using the m_critSection lock means the higher level test for m_pCallback will protect us.