[gnome-shell] st/icon: Fix GIcon leak in set_fallback_icon_name

[Florian Müllner <fmuellner src gnome org>]

commit b49023c31cd38036015a5e637f88f7e5bd2d8029
Author: Sebastian Keller <skeller gnome org>
Date:   Wed Jan 22 23:34:23 2020 +0100

    st/icon: Fix GIcon leak in set_fallback_icon_name
    
    set_fallback_icon_name() leaks a GIcon by using the set_icon method
    which adds a ref to the GIcon without removing its own ref after calling
    the method.
    
    Related to https://gitlab.gnome.org/GNOME/gnome-shell/issues/2146

 src/st/st-icon.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/st/st-icon.c b/src/st/st-icon.c
index 70e4fb46cf..090ba4b10d 100644
--- a/src/st/st-icon.c
+++ b/src/st/st-icon.c
@@ -726,7 +726,7 @@ void
 st_icon_set_fallback_icon_name (StIcon      *icon,
                                 const gchar *fallback_icon_name)
 {
-  GIcon *gicon = NULL;
+  g_autoptr(GIcon) gicon = NULL;
 
   g_return_if_fail (ST_IS_ICON (icon));