Update func_aes to its pre-ast_str_substitution state.

This change makes the AES tests in test_substitution.c pass.  We still need to
work through what's going wrong in the ast_str version.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@243118 65c4cc65-6c06-0410-ace0-fbb531ad65f3