- dynamically allocate the ast_jb structure that is on the channel structure

so that channels not using a jitterbuffer don't waste as much memory
- ensure that the channel drivers that use jitterbuffers can handle a failure
  from configuring a jitterbuffer on a new channel because of a memory
  allocation error
- On passing through these channel drivers, configure the jitterbuffer before
  starting the PBX thread instead of afterwards. If the pbx fails to start for
  whatever reason, this would have caused a crash.
- Also on passing, move the increase of the usecount to after all of the
  possible failure conditions in the function
- fix a place where ast_update_use_count() was not called
- ensure that the owner channel pointer of the channel pvt strcutures is set to
  NULL in failure conditions


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@35553 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_alsa.c

@@ -812,19 +812,23 @@ static struct ast_channel *alsa_new(struct chan_alsa_pvt *p, int state)
 			ast_string_field_set(tmp, language, language);
 		p->owner = tmp;
 		ast_setstate(tmp, state);
-		ast_mutex_lock(&usecnt_lock);
-		usecnt++;
-		ast_mutex_unlock(&usecnt_lock);
-		ast_update_use_count();
+		if (ast_jb_configure(tmp, &global_jbconf)) {
+			ast_hangup(tmp);
+			p->owner = NULL;
+			return NULL;
+		}
 		if (state != AST_STATE_DOWN) {
 			if (ast_pbx_start(tmp)) {
 				ast_log(LOG_WARNING, "Unable to start PBX on %s\n", tmp->name);
 				ast_hangup(tmp);
-				tmp = NULL;
+				p->owner = NULL;
+				return NULL;
 			}
 		}
-		if (tmp)
-			ast_jb_configure(tmp, &global_jbconf);
+		ast_mutex_lock(&usecnt_lock);
+		usecnt++;
+		ast_mutex_unlock(&usecnt_lock);
+		ast_update_use_count();
 	}
 	return tmp;
 }