Increase VIDEO_PICTURE_QUEUE_SIZE to 2.

this allows more asynchronous decoding and display thus improving
video smoothness.
It also seems to improve absolute video decoding speed for some reason

Originally committed as revision 22434 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffplay.c

@@ -87,7 +87,7 @@ typedef struct PacketQueue {
     SDL_cond *cond;
 } PacketQueue;
 
-#define VIDEO_PICTURE_QUEUE_SIZE 1
+#define VIDEO_PICTURE_QUEUE_SIZE 2
 #define SUBPICTURE_QUEUE_SIZE 4
 
 typedef struct VideoPicture {