This parameter is no longer needed.

The algorithm is now always the same, doesn't matter if we're
adding or removing a container to/from its parent.

include/con.h

@@ -112,8 +112,7 @@ void con_detach(Con *con);
  * container.
  *
  */
-void con_fix_percent(Con *con, int action);
-enum { WINDOW_ADD = 0, WINDOW_REMOVE = 1 };
+void con_fix_percent(Con *con);
 
 /**
  * Toggles fullscreen mode for the given container. Fullscreen mode will not be