Add buffer pointer as string in modifier_data for modifier "history_add"

doc/en/weechat_plugin_api.en.txt

@@ -6129,7 +6129,7 @@ Arguments:
   "1" to display bar, "0" to hide it
 
 | weechat | history_add |
-  - |
+  string with buffer pointer ("0x123..") |
   input buffer (from user) added to command history (buffer and global) |
   string added to command history
 

doc/fr/weechat_plugin_api.fr.txt

@@ -6211,7 +6211,7 @@ Paramètres :
   "1" pour afficher la barre, "0" pour la cacher
 
 | weechat | history_add |
-  - |
+  chaîne avec un pointeur vers le tampon ("0x123..") |
   chaîne saisie par l'utilisateur ajoutée à l'historique des commandes (tampon
   et global) |
   chaîne ajoutée à l'historique des commandes

doc/it/weechat_plugin_api.it.txt

@@ -6194,7 +6194,7 @@ Argomenti:
   "1" per visualizzare la barra, "0" per nasconderla
 
 | weechat | history_add |
-  - |
+  stringa con puntatore al buffer ("0x123..") |
   input buffer (from user) added to command history (buffer and global) |
   string added to command history
 

src/gui/gui-history.c

@@ -142,10 +142,12 @@ gui_history_global_add (const char *string)
 void
 gui_history_add (struct t_gui_buffer *buffer, const char *string)
 {
-    char *string2;
+    char *string2, str_buffer[128];
+    
+    snprintf (str_buffer, sizeof (str_buffer),
+              "0x%lx", (long unsigned int)(buffer));
+    string2 = hook_modifier_exec (NULL, "history_add", str_buffer, string);
     
-    string2 = hook_modifier_exec (NULL, "history_add", NULL, string);
-
     /*
      * if message was NOT dropped by modifier, then we add it to buffer and
      * global history