Do not test the deprecated API versions.  debian-win32-cross and debian-win64-cross
are already using SDL2 (they do not cover GTK+ at all).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
[AJB: fix merge conflicts]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>