Place the delay in __ast_answer prior to the channel-specific answer

callback. This change differs from commit 127113 in that now the 
channel is not set to AST_STATE_UP until after the answer callback.

(closes issue #12924)
Reported by: snyfer



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@127157 65c4cc65-6c06-0410-ace0-fbb531ad65f3