gcc 4.4 fix: union instead of cast

gcc 4.4 has more strict rules for aliasing. It doesn't like a 
struct sockaddr_in pointer pointing to a struct sockaddr. So we make it
a union.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@217445 65c4cc65-6c06-0410-ace0-fbb531ad65f3