locking: disable an annoying warning

The warning is wrong when the user has just saved a buffer under a
new name.  And when --quickblank is used, the warning most likely
gets cleared off before it is seen, and the user would just hear
the beep and be left wondering what happened.

This avoids https://savannah.gnu.org/bugs/?49875.

src/files.c

@@ -148,8 +148,9 @@ void set_modified(void)
 
     if (openfile->lock_filename == NULL) {
 	/* TRANSLATORS: Keep the next ten messages at most 76 characters. */
-	statusline(ALERT, _("Warning: Modifying a file which is not locked,"
-			" check directory permission?"));
+//	statusline(ALERT, _("Warning: Modifying a file which is not locked,"
+//			" check directory permission?"));
+	;
     } else {
 	char *fullname = get_full_path(openfile->filename);
 	write_lockfile(openfile->lock_filename, fullname, TRUE);