tests: fix utmpdump/to-text for bigendian

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
tests: fix utmpdump/ipv6totxt for bigendian

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
tests: fix utmpdump/to-binary for bigendian

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>
tests: fix utmpdump/ipv6tobin for bigendian

Signed-off-by: Ruediger Meier <ruediger.meier@ga-group.nl>