sockaddr (in case it's not missing) so it always works on the system that
we are defining it for, in a RFC-2553/3493-compliant way (i.e. containing
a ss_family field). which is used in udp.c. Patch by Martin Storsjö
<$firstname $firstname st>.

Originally committed as revision 21352 to svn://svn.ffmpeg.org/ffmpeg/trunk