patch to fix format hardening in trunk

Dear Abiword team,

building trunk using --with-gtk2 needs one little correction
for format-hardening support as in the attached patch (inlining as well).

Thank you.

Regards,
Dmitry.

--- a/goffice-bits2/goffice/gtk/goffice-gtk.c
+++ b/goffice-bits2/goffice/gtk/goffice-gtk.c
@@ -853,7 +853,7 @@
 <-----><------><------> GTK_DIALOG_DESTROY_WITH_PARENT,
 <-----><------><------> GTK_MESSAGE_WARNING,
 <-----><------><------> GTK_BUTTONS_OK_CANCEL,
-<-----><------><------> msg);
+<-----><------><------> "%s", msg);
 <-----><------>gtk_dialog_set_default_response (GTK_DIALOG (dialog),
 <-----><------><------>overwrite_by_default ? GTK_RESPONSE_OK : GTK_RESPONSE_CANCEL);
 <-----><------>result = GTK_RESPONSE_OK ==