pjstun_get_mapped_addr() failed when receiving incoming SIP request (thanks Lafras Henning)

[bennylp]

pjstun_get_mapped_addr() is the function to resolve the mapped STUN address for given sockets. This is an old/simple STUN implementation in pjlib-util, and is different than the STUN implementation in pjnath.

When pjstun_get_mapped_addr() is called to resolve local SIP socket, and when at the same time other SIP endpoint sends SIP request to pjsip, this function will fail with WSAEMSGSIZE error, because the SIP request is larger than the expected STUN response.

[bennylp]

The solution committed in r1596:

• ignore recvfrom() and parsing error, and continue retransmitting the STUN binding request upon encountering these errors.