_dbus_become_daemon: don't pretend it worked

This function is meaningless (and possibly unimplementable) on Windows.
We shouldn't call it; if we do, it should raise an error.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=68852
Reviewed-by: Ralf Habacker <ralf.habacker@freenet.de>

dbus/dbus-sysdeps-util-win.c

@@ -65,7 +65,9 @@ _dbus_become_daemon (const DBusString *pidfile,
                      DBusError        *error,
                      dbus_bool_t       keep_umask)
 {
-  return TRUE;
+  dbus_set_error (error, DBUS_ERROR_NOT_SUPPORTED,
+                  "Cannot daemonize on Windows");
+  return FALSE;
 }
 
 /**