Allow sin_port = 0 for certain applications

[Tomasz Gebarowski]

In most of the cases sin_port member of struct sockaddr_in should be a non zero value.
There is an exception from that rule for UDP Source Port., see below:

"Normally, the field identifies the sender's port when meaningful and should be assumed to be the port to reply to if needed. If not used, then it should be zero. If the source host is the client, the port number is likely to be an ephemeral port number. If the source host is the server, the port number is likely to be a well-known port number"

Change the jardin_common_new_inet_address to allow sin_port = 0 in certain applications.

[Tomasz Gebarowski (tgebarowski)]

Fix commited in branch:
https://code.launchpad.net/~tgebarowski/eljardin/bugfix-816985

[Tomasz Gebarowski (tgebarowski)]

Regression has been introduced.