statusbar: overwrite a message also when using --constant with --zero

This needlessly wipes the status bar when --constantshow is active,
but it already needlessly wiped it when --minibar is active, so...
It is not a performance issue.  It was just a small optimization.
(Plus, with --zero, nano does a full edit_refresh() when in fact
only the bottom row needs to be redrawn, but there is no easy way
to do that when --softwrap is active, so...)

(Using --constantshow with --zero doesn't make sense, but the user
might want to have the --constantshow when they toggle --zero off.)

src/winio.c

@@ -1701,10 +1701,6 @@ void check_statusblank(void)
 
 	statusblank--;
 
-	/* When editing and 'constantshow' is active, skip the blanking. */
-	if (currmenu == MMAIN && ISSET(CONSTANT_SHOW) && LINES > 1)
-		return;
-
 	if (statusblank == 0)
 		wipe_statusbar();