[perl-Gtk2-Unique] [RT-120115] crash on starting second instance

[Emmanuel Rodriguez <erodriguez src gnome org>]

commit 91e26bdff24a3c5361e572c94d2241baedbe620a
Author: Emmanuel Rodriguez <emmanuel rodriguez gmail com>
Date:   Fri Feb 24 21:35:00 2017 +0100

    [RT-120115] crash on starting second instance
    
    See https://rt.cpan.org/Public/Bug/Display.html?id=120115

 xs/UniqueApp.xs |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/xs/UniqueApp.xs b/xs/UniqueApp.xs
index daba209..cd38bbc 100644
--- a/xs/UniqueApp.xs
+++ b/xs/UniqueApp.xs
@@ -1,6 +1,8 @@
 #include "unique-perl.h"
 #include <gperl_marshal.h>
 
+G_CONST_RETURN gchar * unique_command_to_string (UniqueApp *app, gint command);
+
 static void
 perl_unique_app_marshall_message_received (
        GClosure *closure,