BGE: Fix for bug #34219 "Webcam support under Linux in Standalone broken" reported by Thomas Achtner (offtools).

No one bothered to update the player for ffmpeg changes made in August 2012. This meant the player was no longer calling avdevice_register_all(), and  ffmpeg would fail to open web cam streams.

source/gameengine/GamePlayer/ghost/GPG_ghost.cpp

@@ -449,6 +449,10 @@ int main(int argc, char** argv)
 	IMB_init();
 	BKE_images_init();
 
+#ifdef WITH_FFMPEG
+	IMB_ffmpeg_init();
+#endif
+
 	// Setup builtin font for BLF (mostly copied from creator.c, wm_init_exit.c and interface_style.c)
 	BLF_init(11, U.dpi);
 	BLF_lang_init();