[gdk-pixbuf] tests: Add test for bug 778584

[Bastien Nocera <hadess src gnome org>]

commit af94eab55b43dd959f1d461748cae882579aa02d
Author: Bastien Nocera <hadess hadess net>
Date:   Mon Dec 4 17:10:17 2017 +0100

    tests: Add test for bug 778584
    
    https://bugzilla.gnome.org/show_bug.cgi?id=778584

 tests/test-images/fail/bug778584.gif |  Bin 0 -> 519 bytes
 1 files changed, 0 insertions(+), 0 deletions(-)
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diff --git a/tests/test-images/fail/bug778584.gif b/tests/test-images/fail/bug778584.gif
new file mode 100644
index 0000000..40c580d
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