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/if_perl.xs b/src/if_perl.xs
index 1afb1d4..8923926 100644
--- a/src/if_perl.xs
+++ b/src/if_perl.xs
@@ -1460,7 +1460,7 @@
     FREETMPS;
     LEAVE;
     check_cursor();
-    update_screen(NOT_VALID);
+    update_screen(UPD_NOT_VALID);
     if (!length)
 	return;
 
@@ -1584,7 +1584,7 @@
     PPCODE:
     if (line != NULL)
 	do_set((char_u *)line, 0);
-    update_screen(NOT_VALID);
+    update_screen(UPD_NOT_VALID);
 
 void
 DoCommand(line)
@@ -1777,7 +1777,7 @@
       win->w_cursor.col = col;
       win->w_set_curswant = TRUE;
       check_cursor();		    /* put cursor on an existing line */
-      update_screen(NOT_VALID);
+      update_screen(UPD_NOT_VALID);
     }
 
 MODULE = VIM	    PACKAGE = VIBUF
@@ -1929,7 +1929,7 @@
 		    aucmd_restbuf(&aco);
 		    /* Careful: autocommands may have made "vimbuf" invalid! */
 
-		    update_curbuf(VALID);
+		    update_curbuf(UPD_VALID);
 		}
 	    }
 	}
@@ -1970,7 +1970,7 @@
 		aucmd_restbuf(&aco);
 		/* Careful: autocommands may have made "vimbuf" invalid! */
 
-		update_curbuf(VALID);
+		update_curbuf(UPD_VALID);
 	    }
 	}
     }