[gdk-pixbuf] tests: Add test for rowstride overflow

[Bastien Nocera <hadess src gnome org>]

commit c5b375e26767c140f37b9d1391a0e436c34eaabc
Author: Tobias Mueller <muelli cryptobitch de>
Date:   Thu Feb 16 20:57:17 2017 +0100

    tests: Add test for rowstride overflow
    
    File created using afl.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=777315

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