patch 9.0.1171: screen is not redrawn after using setcellwidths()

Problem:    Screen is not redrawn after using setcellwidths().
Solution:   Redraw the screen when the cell widths have changed. (Yasuhiro
            Matsumoto, closes #11800)
diff --git a/src/mbyte.c b/src/mbyte.c
index aa2b177..1570cef 100644
--- a/src/mbyte.c
+++ b/src/mbyte.c
@@ -5742,6 +5742,7 @@
     }
 
     vim_free(cw_table_save);
+    redraw_all_later(UPD_CLEAR);
 }
 
     void