- Remove debug variable that was only used in one place

 - convert string handling to the ast_str API
 - Convert strdup() to ast_strdup() and check the result
 - Minor formatting changes


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@65749 65c4cc65-6c06-0410-ace0-fbb531ad65f3