[perl-Gtk3] Fix a test failure when no display is available

[Torsten Schönfeld <tsch src gnome org>]

commit 3c70e00cb77afe0e9659ea599b41b2c45f1da514
Author: Torsten Schönfeld <kaffeetisch gmx de>
Date:   Tue Sep 22 22:17:11 2015 +0200

    Fix a test failure when no display is available
    
    The test t/vfuncs-double-setup.t unconditionally called Gtk3::init.

 t/vfuncs-double-setup.t |   15 ++++++++-------
 1 files changed, 8 insertions(+), 7 deletions(-)
---
diff --git a/t/vfuncs-double-setup.t b/t/vfuncs-double-setup.t
index 1f4b084..4a4811b 100644
--- a/t/vfuncs-double-setup.t
+++ b/t/vfuncs-double-setup.t
@@ -22,17 +22,18 @@ use strict;
 use warnings;
 
 # Second import.
-use Gtk3 -init;
+use Gtk3;
 
 use Test::More;
 if (!eval { Glib::Object::Introspection->VERSION ('0.030') }) {
   plan skip_all => 'G:O:I 0.030 required';
-} else {
-  plan tests => 1;
 }
+if (!Gtk3::init_check ()) {
+  plan skip_all => 'Gtk3::init_check failed';
+}
+plan tests => 1;
 
-my $window = Gtk3::Window->new();
-$window->signal_connect(delete_event => sub { Gtk3->main_quit() });
-my $my_button = MyButton->new(label => "Test");
-$window->add($my_button);
+my $window = Gtk3::Window->new;
+my $my_button = MyButton->new (label => "Test");
+$window->add ($my_button); # trigger PARENT_SET
 pass;