Don't always store messages passed through muc_filter_message

Recently we added new places where we call muc_filter_message to add
occupandid info to messages, but this also made them be stored in archive
as mod_mam uses that hook for getting sent messages - in case of those
messages we shouldn't be doing this.

This should fix issue #4083

src/mod_mam.erl

@@ -465,6 +465,8 @@ offline_message({_Action, #message{from = Peer, to = To} = Pkt} = Acc) ->
 
 -spec muc_filter_message(message(), mod_muc_room:state(),
 			 binary()) -> message().
+muc_filter_message(#message{meta = #{mam_ignore := true}} = Pkt, _MUCState, _FromNick) ->
+    Pkt;
 muc_filter_message(#message{from = From} = Pkt,
 		   #state{config = Config, jid = RoomJID} = MUCState,
 		   FromNick) ->

src/mod_muc_room.erl

@@ -625,12 +625,12 @@ normal_state({route, ToNick,
                                     Packet2 = xmpp:set_subtag(Packet, X),
                                     case ejabberd_hooks:run_fold(muc_filter_message,
                                                                  StateData#state.server_host,
-                                                                 Packet2,
+								 xmpp:put_meta(Packet2, mam_ignore, true),
                                                                  [StateData, FromNick]) of
                                         drop ->
                                             ok;
                                         Packet3 ->
-                                            PrivMsg = xmpp:set_from(Packet3, FromNickJID),
+                                            PrivMsg = xmpp:set_from(xmpp:del_meta(Packet3, mam_ignore), FromNickJID),
                                             lists:foreach(
                                               fun(ToJID) ->
                                                       ejabberd_router:route(xmpp:set_to(PrivMsg, ToJID))
@@ -3016,7 +3016,7 @@ send_subject(JID, #state{subject_author = {Nick, AuthorJID}} = StateData) ->
 		      to = JID, type = groupchat, subject = Subject},
     case ejabberd_hooks:run_fold(muc_filter_message,
                                  StateData#state.server_host,
-                                 Packet,
+                                 xmpp:put_meta(Packet, mam_ignore, true),
                                  [StateData, Nick]) of
         drop ->
             ok;
@@ -5169,9 +5169,9 @@ process_iq_moderate(From, #iq{type = set, lang = Lang},
 					  ]}]},
 	            {FromNick, _Role} = get_participant_data(From, StateData),
                     Packet = ejabberd_hooks:run_fold(muc_filter_message,
-                                                                 StateData#state.server_host,
-                                                                 Packet0,
-                                                                 [StateData, FromNick]),
+						     StateData#state.server_host,
+						     xmpp:put_meta(Packet0, mam_ignore, true),
+						     [StateData, FromNick]),
 		    send_wrapped_multiple(JID,
 					  get_users_and_subscribers_with_node(?NS_MUCSUB_NODES_MESSAGES, StateData),
 					  Packet, ?NS_MUCSUB_NODES_MESSAGES, StateData),