[gthumb] fixed compiler warnings

[Paolo Bacchilega <paobac src gnome org>]

commit 982ab386db2122bfba757f5f24dedbfb64fe5757
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Sat Apr 4 21:27:41 2015 +0200

    fixed compiler warnings

 gthumb/gth-main.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gthumb/gth-main.c b/gthumb/gth-main.c
index 7f6e1fa..9dddfa9 100644
--- a/gthumb/gth-main.c
+++ b/gthumb/gth-main.c
@@ -1267,7 +1267,7 @@ gth_main_activate_extensions (void)
                user_actived_extensions = g_strdupv ((char **) default_extensions);
                g_settings_set_strv (settings, PREF_GENERAL_ACTIVE_EXTENSIONS, (const char *const *) 
user_actived_extensions);
        }
-       actived_extensions = _g_strv_concat (mandatory_extensions, user_actived_extensions);
+       actived_extensions = _g_strv_concat ((char **) mandatory_extensions, user_actived_extensions);
        ordered_extensions = gth_extension_manager_order_extensions (Main->priv->extension_manager, 
actived_extensions);
 
        manager = gth_main_get_default_extension_manager ();
@@ -1277,7 +1277,7 @@ gth_main_activate_extensions (void)
                GthExtensionDescription *description;
                GError                  *error = NULL;
 
-               mandatory = _g_strv_contains (mandatory_extensions, name);
+               mandatory = _g_strv_contains ((char **) mandatory_extensions, name);
                description = gth_extension_manager_get_description (manager, name);
                if (! mandatory && (description != NULL) && description->hidden)
                        continue;