- Remove redundant forward declaration

- Change variable name to make register_verify more readable (p -> peer not pvt in this function)
- Get Contact: header only once instead of twice
- Add some comments to register_verify

Caused by issue #7327... :-)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@33614 65c4cc65-6c06-0410-ace0-fbb531ad65f3