[editor] Reset _currentSegment on cleanup, otherwise we may crash loa…

…ding next video if seek to the first frame fails

avidemux/common/ADM_editor/src/ADM_edit.cpp

@@ -521,6 +521,7 @@ uint8_t ADM_Composer::cleanup (void)
 
   _segments.deleteAll();
   _currentPts = 0;
+  _currentSegment = 0;
   markerAPts = 0;
   markerBPts = 0;
   audioTrackPool.clear();