- localize 'struct cfalias' into the only function using it;

- remove duplicate code to walk through sdp packets, replacing
  sdpLineNum_iterator_init(&foo); with  "foo = 0";
- remove duplicate code to test ast_test_flag(&p->flags[0], SIP_NAT_ROUTE);



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@18791 65c4cc65-6c06-0410-ace0-fbb531ad65f3