avcodec/snowenc: change log level for iterative ME information to debug level

The printed stuff should be useless to the average user and its certainly
not an error.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/snowenc.c

@@ -1155,7 +1155,7 @@ static void iterative_me(SnowContext *s){
                 }
             }
         }
-        av_log(s->avctx, AV_LOG_ERROR, "pass:%d changed:%d\n", pass, change);
+        av_log(s->avctx, AV_LOG_DEBUG, "pass:%d changed:%d\n", pass, change);
         if(!change)
             break;
     }