Skinny: fix up possible double unlock of chan.

Return before chan is possibly unlocked a second time when hanging up
a channel in SUBSTATE_OFFHOOK.
........

Merged revisions 406987 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@406988 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_skinny.c

@@ -5799,6 +5799,7 @@ static void setsubstate(struct skinny_subchannel *sub, int state)
 				sub->substate = SUBSTATE_ONHOOK;
 				skinny_unlocksub(sub);
 				ast_hangup(sub->owner);
+				return;
 			} else {
 				sub->substate = SUBSTATE_ONHOOK;
 				ast_queue_hangup(sub->owner);