There are a few remaining explicit uses of http://www.freebsd.org/cgi/
but all of these appear to be outdated e.g. pointing to GNATS) and need
updating.
Switch &cgibase; to use protocol-relative links, rather than hardcoding
http. Switch two others (ftpbase and ftpbaseerrata) whilst here.
- Replace /XML/{doc,www}/ with /XML/ in SysId.
- Remove empty stylesheets in share/xsl and point share/xml/empty.xsl via
XML catalog instead.
- Change the L10N layer in freebsd-*.xsl not to use localized XSLT
stylesheets directly.
- Move share/xsl/* to share/xml and remove share/xsl.
- Remove obsolete share/web2c/pdftex.def.
