[gnome-panel] panel-utils: fix cast-function-type warning

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 5b3511a9b9474329ce10955b8aedc57446b50278
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Mon Sep 17 20:42:01 2018 +0300

    panel-utils: fix cast-function-type warning

 gnome-panel/panel-util.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
---
diff --git a/gnome-panel/panel-util.c b/gnome-panel/panel-util.c
index 9ee387d11..163436773 100644
--- a/gnome-panel/panel-util.c
+++ b/gnome-panel/panel-util.c
@@ -935,6 +935,13 @@ panel_util_query_tooltip_cb (GtkWidget  *widget,
        return TRUE;
 }
 
+static void
+free_tooltip (gchar    *tooltip,
+              GClosure *closure)
+{
+       g_free (tooltip);
+}
+
 void
 panel_util_set_tooltip_text (GtkWidget  *widget,
                             const char *text)
@@ -953,7 +960,7 @@ panel_util_set_tooltip_text (GtkWidget  *widget,
        g_object_set (widget, "has-tooltip", TRUE, NULL);
        g_signal_connect_data (widget, "query-tooltip",
                               G_CALLBACK (panel_util_query_tooltip_cb),
-                              g_strdup (text), (GClosureNotify) g_free, 0);
+                              g_strdup (text), (GClosureNotify) free_tooltip, 0);
 }
 
 /* This is similar to what g_file_new_for_commandline_arg() does, but