*/*: Rework manpages handling in Samba-related ports
- Remove outdated, incorrect, precompiled manpages from ${FILESDIR}/files/man.
- Properly disable manpages generation since XSLTPROC was set to true(1) WAF always assumed xsltproc(1) to work and if any automatic dependency pulled in textproc/docbook-xsl, manpages were generated even if explicitly disabled.
Approved by: jrm (mentor)
Differential Revision: https://reviews.freebsd.org/D49327