core: allow multiple hotkeys for the same action

Hotkeys are separated by tabs. I would have allowed white spaces, but
they are found in some media key names :-(

src/config/keys.c

@@ -370,6 +370,7 @@ static int vlc_key_to_action (vlc_object_t *libvlc, const char *varname,
  */
 struct vlc_actions *vlc_InitActions (libvlc_int_t *libvlc)
 {
+    vlc_object_t *obj = VLC_OBJECT(libvlc);
     struct hotkey *keys;
     struct vlc_actions *as = malloc (sizeof (*as) + (ACTIONS_COUNT + 1) * sizeof (*keys));
 
@@ -397,11 +398,21 @@ struct vlc_actions *vlc_InitActions (libvlc_int_t *libvlc)
         keys->i_action = actions[i].value;
         keys++;
 
-        char *str = var_InheritString (libvlc, actions[i].name);
-        uint32_t code = str ? vlc_str2keycode (str) : KEY_UNSET;
+        char *str = var_InheritString (obj, actions[i].name);
+        if (str == NULL)
+            continue;
+
+        for (char *buf, *key = strtok_r (str, "\t", &buf);
+             key != NULL;
+             key = strtok_r (NULL, "\t", &buf))
+        {
+            uint32_t code = vlc_str2keycode (key);
 
             if (code == KEY_UNSET)
+            {
+                msg_Warn (obj, "Key \"%s\" unrecognized", key);
                 continue;
+            }
 
             struct mapping *entry = malloc (sizeof (*entry));
             if (entry == NULL)
@@ -415,8 +426,8 @@ struct vlc_actions *vlc_InitActions (libvlc_int_t *libvlc)
             if (*pent != entry)
             {
                 free (entry);
-            msg_Warn (libvlc, "Key code \"%s\" bound to multiple actions",
-                      str);
+                msg_Warn (obj, "Key \"%s\" bound to multiple actions", key);
+            }
         }
         free (str);
     }