Mark channel running the h exten with the soft-hangup flag.

Mark channel running the h exten with the soft-hangup flag.

When a bridge is broken, ast_bridge_call() might execute the h exten on
the calling channel.  However, that channel may not have been the channel
that broke the bridge by hanging up.  The channel executing the h exten
must be in a hung up state so things like AGI run in the correct mode.

* Make sure ast_bridge_call() marks the channel it is executing the h
exten on as hung up.  (The AST_SOFTHANGUP_APPUNLOAD flag is used so as to
match the pbx.c main dialplan execution loop when it executes the h
exten.)

(closes issue ASTERISK-18811)
Reported by: David Hajek
Patches:
      jira_asterisk_18811_v1.8.patch (license #5621) patch uploaded by rmudgett
Tested by: David Hajek, rmudgett

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@347595 65c4cc65-6c06-0410-ace0-fbb531ad65f3