[tlbuild] Harfbuzz 4.4.x

[Karl Berry]

If a simple patch to hb avoiding this silly C++ problem solves the
problem, that seems like a good thing to do. Maybe they would even
accept it upstream. Heck, maybe someone else has already figured it out;
I doubt we're the only people using older compilers.

As we know from Macs, just because something reaches EOL doesn't mean
people will stop using it. I expect people will be using Solaris 10 for
quite some time. (Old Debian, maybe not so much.)  However, it's up to
you, or whoever volunteers to build binaries, as to what you provide.
If you prefer to move to Solaris 11, that's fine.

Also, I surmise Nelson will continue to provide binaries for many older
systems as long as he can, so people can get them that way too.

    [CentOS] changed their model

Indeed, and the new CentOS 8 Stream is useless -- Red Hat turned it into
a beta test for RHEL.  Fortunately there are multiple distribution
projects based on RHEL 8, with the same approach as CentOS 7.  I'm in
the (slow) process of moving tug.org to one of them, Alma Linux.

But this does not affect CentOS 7; thankfully, RH hasn't killed that one
off.  As far as TL compilation goes, CentOS 7 doesn't reach EOL until
June 2024.

Fortunately, as we discovered last year, RH makes it simple to build on
CentOS 7, in particular against CentOS 7 libc, with a newer compiler,
via their "devtoolset" packages. Thus we (Norbert) are building the
x86_64-linux on CentOS 7 but with gcc 9. -k