- Set IP_RECVDSTADDR sockopt on the socket only in case if
it is INADDR_ANY bound.
- Supply IP_SENDSRCADDR control message only if we did receive
IP_RECVDSTADDR control message.
This fixes operation of snmpd bound to a specific local IP address.
PR: bin/171279
IP_SENDSRCADDR control with datagram message we reply with. This makes
bsnmpd reply from exactly same address that request was sent to, thus
successfully bypassing stateful firewalls or other kinds of strict checking.
PR: bin/171279