do not try to connect a tcp socket with no destination address to connect to. Fixes coverity check when dereferencing addr

Keep the upnp and upnp-timeout properties available even if upnp is disabled during build. This is to prevent a break of the API from one build to another

do not cast time_t and clock_t into unsigned long, on some systems (kfreebsd), it can lead to an error because of strict-aliasing

use sizeof struct sockaddr_in instead of sizeof struct sockaddr to hopefully fix the bug with sendmsg on BSD systems

there's no need to use a memcpy for checking the username's validity in an incoming connectivity check

use g_strlcpy instead of strncpy and memcpy for the candidate foundation, because it makes sure we have a trailing null char in our string.

Increase test-bind timeout to 20 seconds since it was 10 and it took more than 9 seconds for the test.. so it would fail on some slower systems

Even for UDP sockets, we should handle EAGAIN errors because it can happen.. Apparently recvfrom can return EAGAIN on udp sockets if for example there's a bad checksum in the packet or some other similar error

Fix a crash in case a relay candidate could not be added (because of an error or because it's a redundant candidate), do not try to refresh it

Once we process the pending checks, we should free them to avoid reprocessing them again if a dribble-mode set_remote_candidates is called