libnotify: Make gtk+3 dependency optional
libnotify only requires gtk+3 for its tests. Let's disable them by
default and only enable them if "tests" is in PACKAGECONFIG. If gtk+3 is
not available then we need to declare the dependency on gdk-pixbuf
explicitly.
It looks like the tests genuinely do need some sort of desktop
environment to run, so let's maintain the ANY_OF_DISTRO_FEATURES check
added back in
3edf08b38b0af93cef0933b061349264dc86d54c.
Signed-off-by: Mike Crowe <mac@mcrowe.com>
Cc: Khem Raj <raj.khem@gmail.com>
Cc: Alexander Kanavin <alex.kanavin@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
