relay: check that pointers received in arguments are not NULL in "free" functions

Functions:
- relay_irc_free
- relay_client_outqueue_free
- relay_raw_message_free
- relay_weechat_msg_free
- relay_weechat_nicklist_item_free
- relay_weechat_nicklist_free
- relay_weechat_free

src/plugins/relay/irc/relay-irc.c

@@ -1859,6 +1859,9 @@ relay_irc_alloc_with_infolist (struct t_relay_client *client,
 void
 relay_irc_free (struct t_relay_client *client)
 {
+    if (!client)
+        return;
+
     if (client->protocol_data)
     {
         if (RELAY_IRC_DATA(client, address))

src/plugins/relay/relay-client.c

@@ -757,6 +757,9 @@ relay_client_outqueue_free (struct t_relay_client *client,
 {
     struct t_relay_client_outqueue *new_outqueue;
 
+    if (!client || !outqueue)
+        return;
+
     /* remove outqueue message */
     if (client->last_outqueue == outqueue)
         client->last_outqueue = outqueue->prev_outqueue;

src/plugins/relay/relay-raw.c

@@ -119,6 +119,9 @@ relay_raw_message_free (struct t_relay_raw_message *raw_message)
 {
     struct t_relay_raw_message *new_raw_messages;
 
+    if (!raw_message)
+        return;
+
     /* remove message from raw messages list */
     if (last_relay_raw_message == raw_message)
         last_relay_raw_message = raw_message->prev_message;

src/plugins/relay/weechat/relay-weechat-msg.c

@@ -1095,6 +1095,9 @@ relay_weechat_msg_send (struct t_relay_client *client,
 void
 relay_weechat_msg_free (struct t_relay_weechat_msg *msg)
 {
+    if (!msg)
+        return;
+
     if (msg->id)
         free (msg->id);
     if (msg->data)

src/plugins/relay/weechat/relay-weechat-nicklist.c

@@ -122,6 +122,9 @@ relay_weechat_nicklist_add_item (struct t_relay_weechat_nicklist *nicklist,
 void
 relay_weechat_nicklist_item_free (struct t_relay_weechat_nicklist_item *item)
 {
+    if (!item)
+        return;
+
     if (item->name)
         free (item->name);
     if (item->color)
@@ -141,6 +144,9 @@ relay_weechat_nicklist_free (struct t_relay_weechat_nicklist *nicklist)
 {
     int i;
 
+    if (!nicklist)
+        return;
+
     /* free items */
     if (nicklist->items_count > 0)
     {

src/plugins/relay/weechat/relay-weechat.c

@@ -277,6 +277,9 @@ relay_weechat_alloc_with_infolist (struct t_relay_client *client,
 void
 relay_weechat_free (struct t_relay_client *client)
 {
+    if (!client)
+        return;
+
     if (client->protocol_data)
     {
         if (RELAY_WEECHAT_DATA(client, buffers_sync))