misc/susv*: fix fallout from PR#230864/c479406, misc fixes

susv2, update URLs to keep things downloadable
susv3, add a more direct access link
susv4, update to newer version (2018 edition), revise pkg-descr

susv2, susv3: add the file revision date to PORTVERSION for consistency and
transparency.

all: add OPTIONS_SLAVE=DOCS because it is no good installing an empty port,
systems that do not want documentation shall not install these ports.

all: Reshuffle Makefile lines to reduce number of portlint warnings.