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.
On some systems with libtcl installed, it might be linked into instant
rather than the locally provided version. This can result in random
coredumps.
Seen on Ubuntu 12.04, x86_64.
Now, we force linking with ../tcl/libtcl.a.
