res_pjsip_registrar_expire.c: Made use ao2 container template routines and eliminated some RAII_VAR() usage.

* Converted the contact_autoexpire container to use the ao2 template hash
and cmp functions.  Also made use the OBJ_SEARCH_xxx names instead of the
deprecated names.

* Eliminates several unnecessary uses of RAII_VAR().

Review: https://reviewboard.asterisk.org/r/4524/
........

Merged revisions 433622 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@433623 65c4cc65-6c06-0410-ace0-fbb531ad65f3