patch 9.0.0206: redraw flags are not named specifically

Problem:    Redraw flags are not named specifically.
Solution:   Prefix "UPD_" to the flags, for UPDate_screen().
diff --git a/src/spell.c b/src/spell.c
index 8ca9313..08f627d 100644
--- a/src/spell.c
+++ b/src/spell.c
@@ -2284,7 +2284,7 @@
 		}
 	    }
     }
-    redraw_win_later(wp, NOT_VALID);
+    redraw_win_later(wp, UPD_NOT_VALID);
 
 theend:
     vim_free(spl_copy);
@@ -3854,7 +3854,7 @@
     if (curbuf->b_ml.ml_line_count > 1)
 	ml_delete(curbuf->b_ml.ml_line_count);
 
-    redraw_later(NOT_VALID);
+    redraw_later(UPD_NOT_VALID);
 }
 
 /*