closes issue #11294; missed the conditional unlock of the contexts when the...

closes issue #11294; missed the conditional unlock of the contexts when the hash table is used instead; also, used the ast_free_ptr as advised.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@89792 65c4cc65-6c06-0410-ace0-fbb531ad65f3