Fix a problem with the use of control structures in sendmsg / recvmsg. These are not struct sockaddr, they are ip_pktinfo or ipv6_pktinfo, so local_interface->addr.size is irrelevant, even causing an overflow with writing zero bytes outside of the control structure on the stack, even though it happens to work because the buffer is large enough. Prevent invalid addresses from being used as source address with sendmsg. On linux, they are just ignored, so it is the same as not specifying one, but on windows they cause an error. In both case it is simpler not to include any control info if the intent is to let the interface be chosen by the network stack.
Fix a problem with the use of control structures in sendmsg / recvmsg. These are not struct sockaddr, they are ip_pktinfo or ipv6_pktinfo, so local_interface->addr.size is irrelevant, even causing an overflow with writing zero bytes outside of the control structure on the stack, even though it happens to work because the buffer is large enough.
Prevent invalid addresses from being used as source address with sendmsg. On linux, they are just ignored, so it is the same as not specifying one, but on windows they cause an error. In both case it is simpler not to include any control info if the intent is to let the interface be chosen by the network stack.

authmillenon/libcoap,authmillenon/libcoap,authmillenon/libcoap