docbook.tcl, instant: finish remaining help generation issues with tcl

docbook.tcl, instant: finish remaining help generation issues with tcl

In this commit, we convert FreeBSD and OpenBSD to use a system version
of TCL (8.6).

We also get rid of the hairy and buggy "CompareI18NStrings" custom Tcl
function and use the newer Tcl's builtin dictionary sort mechanism for
generating the Indexes and Glossaries, which were silently broken in
previous commits.

It was just not possible to use the same Tcl code in modern versions
of Tcl in addition to the ancient version included with CDE - so, now
we will always depend on the system version.  It's been tested with
8.6 and 8.7 versions of Tcl with great results.