Huffyuv: Remove unnecessary allocation in alloc_temp().

RGB only needs one temp array.

Originally committed as revision 20258 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/huffyuv.c

@@ -406,9 +406,7 @@ static av_cold void alloc_temp(HYuvContext *s){
             s->temp[i]= av_malloc(s->width + 16);
         }
     }else{
-        for(i=0; i<2; i++){
+        s->temp[0]= av_malloc(4*s->width + 16);
-            s->temp[i]= av_malloc(4*s->width + 16);
-        }
     }
 }