libubus: mark ubus socket with close-on-exec

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
libubus: fix msgbuf reduction logic during receive

Signed-off-by: Alexandru Ardelean <aa@ocedo.com>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
libubus: fix a small memleak in ubus_register_event_handler()

Signed-off-by: Felix Fietkau <nbd@openwrt.org>