MOH for only user not working with ConfBridge

This adds the playing_moh flag to the conference_bridge_user struct that
signifies when MOH should be playing so code doesn't have to guess whether
MOH is playing.

This change also adds the necessary checking to ensure that MOH continues
playing for a single user in a conference after the join sound is played when
configured to do so.

(closes ASTERISK-17988)
Review: https://reviewboard.asterisk.org/r/1263/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@323107 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/confbridge/include/confbridge.h

@@ -215,6 +215,7 @@ struct conference_bridge_user {
 	struct ast_bridge_features features;         /*!< Bridge features structure */
 	struct ast_bridge_tech_optimizations tech_args; /*!< Bridge technology optimizations for talk detection */
 	unsigned int kicked:1;                       /*!< User has been kicked from the conference */
+	unsigned int playing_moh:1;                  /*!< MOH is currently being played to the user */
 	AST_LIST_ENTRY(conference_bridge_user) list; /*!< Linked list information */
 };