avutil/downmix_info: add missing semicolon

Fixes compilation broken by 8a72775d5dba3253c4ffd9b7ec91f73beda42641.

Signed-off-by: James Almer <jamrial@gmail.com>

libavutil/downmix_info.c

@@ -31,7 +31,7 @@ AVDownmixInfo *av_downmix_info_update_side_data(AVFrame *frame)
         side_data = av_frame_new_side_data(frame, AV_FRAME_DATA_DOWNMIX_INFO,
                                            sizeof(AVDownmixInfo));
         if (side_data)
-            memset(side_data->data, 0, sizeof(AVDownmixInfo))
+            memset(side_data->data, 0, sizeof(AVDownmixInfo));
     }
 
     if (!side_data)