Initialize outputed_poc to INT_MIN at decoder initialization.

Fixes issue 560

Originally committed as revision 14428 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/h264.c

@@ -2192,6 +2192,7 @@ static av_cold int decode_init(AVCodecContext *avctx){
     }
 
     h->thread_context[0] = h;
+    h->outputed_poc = INT_MIN;
     return 0;
 }