core: fix crash on plugin reload when using musl libs (closes #2052)

src/plugins/relay/relay-config.c

@@ -1460,6 +1460,7 @@ void
 relay_config_free ()
 {
     weechat_config_free (relay_config_file);
+    relay_config_file = NULL;
 
     if (relay_config_regex_allowed_ips)
     {

src/plugins/relay/relay-network.c

@@ -162,6 +162,9 @@ relay_network_set_priority ()
 void
 relay_network_init ()
 {
+    relay_network_init_ok = 0;
+    relay_network_init_tls_cert_key_ok = 0;
+
     /* credentials */
     gnutls_certificate_allocate_credentials (&relay_gnutls_x509_cred);
     relay_network_set_tls_cert_key (0);

src/plugins/relay/relay.c

@@ -203,6 +203,8 @@ weechat_plugin_init (struct t_weechat_plugin *plugin, int argc, char *argv[])
 
     weechat_plugin = plugin;
 
+    relay_signal_upgrade_received = 0;
+
     if (!relay_config_init ())
         return WEECHAT_RC_ERROR;
 
@@ -240,7 +242,10 @@ weechat_plugin_end (struct t_weechat_plugin *plugin)
     (void) plugin;
 
     if (relay_hook_timer)
+    {
         weechat_unhook (relay_hook_timer);
+        relay_hook_timer = NULL;
+    }
 
     relay_config_write ();
 
@@ -254,7 +259,11 @@ weechat_plugin_end (struct t_weechat_plugin *plugin)
     relay_server_free_all ();
 
     if (relay_buffer)
+    {
         weechat_buffer_close (relay_buffer);
+        relay_buffer = NULL;
+    }
+    relay_buffer_selected_line = 0;
 
     relay_client_free_all ();