[gdk-pixbuf] Fix test failure if PNG_iTXt_SUPPORTED not defined

[Robert Ancell <rancell src gnome org>]

commit 18a95ab1b05f6be9607636c5bcbb031c0513e362
Author: Rober Ancell <robert ancell canonical com>
Date:   Wed Jan 15 11:26:08 2014 +1300

    Fix test failure if PNG_iTXt_SUPPORTED not defined

 tests/pixbuf-save.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/tests/pixbuf-save.c b/tests/pixbuf-save.c
index 227f98d..f7df29b 100644
--- a/tests/pixbuf-save.c
+++ b/tests/pixbuf-save.c
@@ -104,7 +104,9 @@ test_save_options (void)
   gdk_pixbuf_save (ref, "pixbuf-save-options", "png", &error,
                    "tEXt::option1", "Some text to transport via option",
                    "tEXt::long-option-name123456789123456789123456789", "",
+#ifdef PNG_iTXt_SUPPORTED
                    "tEXt::3", "αβγδ",
+#endif
                    NULL);
   g_assert_no_error (error);
 
@@ -113,7 +115,9 @@ test_save_options (void)
 
   g_assert_cmpstr (gdk_pixbuf_get_option (pixbuf, "tEXt::option1"), ==, "Some text to transport via option");
   g_assert_cmpstr (gdk_pixbuf_get_option (pixbuf, "tEXt::long-option-name123456789123456789123456789"), ==, 
"");
+#ifdef PNG_iTXt_SUPPORTED
   g_assert_cmpstr (gdk_pixbuf_get_option (pixbuf, "tEXt::3"), ==, "αβγδ");
+#endif
 
   g_object_unref (pixbuf);
   g_object_unref (ref);