Use the complete definition of the prototype function gtk_style_render_icon.

This solves FTBFS in checking the compatibility of pointers.

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit 38f56e9703)

src/qt_theme_draw.c

@@ -32,7 +32,13 @@
 
 extern gboolean tde_showIconsOnPushButtons;
 
-static GdkPixbuf * (*stockRenderIcon)() = NULL;
+static GdkPixbuf * (*stockRenderIcon)(GtkStyle*,
+                        const GtkIconSource*,
+                        GtkTextDirection,
+                        GtkStateType,
+                        GtkIconSize,
+                        GtkWidget*,
+                        const gchar*) = NULL;
 // static void * (*stockDrawString)() = NULL;
 
 static void qtengine_style_init       (QtEngineStyle      *style);