Refresh the man-refs.ent file from head/.

Sponsored by:	The FreeBSD Foundation
Add a few tweaks to missing-manrefs.sh:

 - In build_manpages(), specify -DNO_ROOT to suppress
   false errors when the 'hier' target gets kicked.

   While here, create a tgz package containing the
   /usr/share/man and /usr/share/openssl to make it
   easier to refresh the man.cgi backend.

 - In add_manref(), work around a recurring issue where
   the add-manref.sh script thinks 'atf-c++-api' is
   a valid entity entry.

   Also fix the section ID passed to add-manref.sh,
   which by the looks of it, should have never worked
   in the first place.

   Use realpath(1) to when passing the target file,
   manual page, and section to add-manref.sh so using
   '.' to specify the current working directory for
   either the path to src/ or doc/ are valid.

Sponsored by:	The FreeBSD Foundation
Remove old so@ key which was expired and keep only the current one.