anv: fold the tests' makefile

Recent commit removed the winsys defines from anv_private.h thus
breaking the tests. To fix that and avoid it in the future, merge the
tests makefile in the libvulkan one.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
3 files changed