tests/acceptance: Add test that runs NetBSD 4.0 installer on PRep/40p

tests/acceptance: Add test that runs NetBSD 4.0 installer on PRep/40p

As of this commit, NetBSD 4.0 is very old. However it is enough to
test the PRep/40p machine.

User case from:
http://mail-index.netbsd.org/port-prep/2017/04/11/msg000112.html

Reviewed-by: Hervé Poussineau <[email protected]>
Acked-by: David Gibson <[email protected]>
Acked-by: Artyom Tarasenko <[email protected]>
Signed-off-by: Philippe Mathieu-Daudé <[email protected]>
Message-Id: <20191028073441[email protected]>
Reviewed-by: Cleber Rosa <[email protected]>
Tested-by: Cleber Rosa <[email protected]>
[Cleber: fixed file name and imports]
Signed-off-by: Cleber Rosa <[email protected]>