strip a leading "v" when it's followed by what looks like a version number,
also have it handle a few other common names seen in ports. likewise when
stripping 'v' from the default WRKDIST, also allow 'V', but only if
followed by digits (which seems a better match to what github are doing).
update the few ports which _require_ updates to match this change.
been through a bulk on i386 (plus I've diffed "make dump-vars" run in
in all ports having GH_TAGNAME before+after applying the patch), ok jca
f69d1135ed