Backing out most of changeset 5222b8db3fb692e5071bfd1b41849a8eb0a17995

Backing out most of changeset 5222b8db3fb692e5071bfd1b41849a8eb0a17995
(so parsing for domain parameter in mount.cifs matches online help)
and rephrasing original code to make it more clear.

The check for "domain" was meant to allow for "dom" or "DOM" and the
option ("dom") described in the help (e.g. "/sbin/mount.cifs -?") is the
shorter ("dom") form.  The reason that the string we compare against
is larger was to improve readability (we could compare against "dom"
but note /* "domain" or "DOMAIN" or "dom" or "DOM" */ but it seemed
terser to just show the larger string in the strcmp target.   The
change to "workgoup" from workg* (anything which begins with "workg"
doesn't matter - it is a minor behavior change - but probably few
scripts depend on the "alias" for this option).

Rework code so that it is clearer what we are comparing against.
(This used to be commit 92fad0fc537e75c726d5d6794dd0c4fd61edca2d)