Fix last received chat message not being marked as read.

coreapi/chat.c

@@ -750,6 +750,10 @@ LinphoneReason linphone_core_message_received(LinphoneCore *lc, SalOp *op, const
 			cr->unread_count = 1;
 		else
 			cr->unread_count++;
+		/* Mark the message as pending so that if linphone_core_chat_room_mark_as_read() is called
+		   in the linphone_chat_room_message_received() callback, it will effectively be marked as
+		   being read before being stored. */
+		cr->pending_message = msg;
 	}
 
 	linphone_chat_room_message_received(cr, lc, msg);
@@ -758,6 +762,8 @@ LinphoneReason linphone_core_message_received(LinphoneCore *lc, SalOp *op, const
 		msg->storage_id = linphone_chat_message_store(msg);
 	}
 
+	cr->pending_message = NULL;
+
 end:
 	linphone_address_unref(addr);
 	if (msg != NULL) linphone_chat_message_unref(msg);

coreapi/message_storage.c

@@ -456,6 +456,11 @@ void linphone_chat_room_mark_as_read(LinphoneChatRoom *cr){
 	sqlite3_free(buf);
 	ms_free(peer);
 
+	if (cr->pending_message) {
+		linphone_chat_message_set_state(cr->pending_message, LinphoneChatMessageStateDisplayed);
+		linphone_chat_message_send_display_notification(cr->pending_message);
+	}
+
 	cr->unread_count = 0;
 }