udev/udev-ctrl.c:udev_ctrl_new_from_fd() enable SO_PASSCRED

Avoid "sender uid=65534, message ignored" case, where no credentials can
be read on the sender side.

Seems, the server socket does not enable credential receiving fast
enough, and the message from the client (without credential) sometimes
is queued before the credential passing was active.

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>