fix: don't override statusbar if info script doesn't exist

this happens when the keyhandler is invoked while viewing an animated
image. if {image,thumb}-info scripts exists, everything works as
expected. but if they don't, then update_info will override the
statusbar.

main.c

@@ -400,7 +400,7 @@ static void update_info(void)
 	win_bar_t *l = &win.bar.l, *r = &win.bar.r;
 
 	/* update bar contents */
-	if (win.bar.h == 0)
+	if (win.bar.h == 0 || extprefix)
 		return;
 	for (fw = 0, i = filecnt; i > 0; fw++, i /= 10);
 	mark = files[fileidx].flags & FF_MARK ? "* " : "";