smlng fd718dfc74 gnrc_udp: assert ports not zero
UDP port 0 is reserved for system usage, e.g., to tell the OS to
    set a random source port. Hence, neither source nor destination
    port should be 0 when transmitting. This PR adds proper asserts.
2018-08-06 16:09:22 +02:00
..
2018-08-06 16:09:22 +02:00