[tlbuild] tl24 build plans

[Karl Berry]

Regarding building for TL24.  Hans told me that Mojca's machine has been
down for some months (http://dl.contextgarden.net/ brings up a default
Apache page), so I don't know if it will be available for TL builds this
year. (Mojca, are you there? Clearly status info from you would be great. :)

Her builds were:
  amd64-freebsd i386-freebsd i386-solaris x86_64-solaris
  aarch64-linux armhf-linux
  x86_64-darwinlegacy

Of those, Norbert found that freebsd and solaris are supported on github:
  https://github.com/marketplace/actions/freebsd-vm
  https://github.com/vmactions/solaris-vm
(Not sure if 32-bit is supported, but maybe the world won't come
to an end if we drop 32-bit freebsd and solaris anyway.)

aarch64 and armhf, I don't know about. Would anyone miss them?

x86_64-darwinlegacy would surely be missed, but who can build it?

No need for any immediate action, just trying to get a glimmer of a plan
together ... --thanks, karl.

P.S. Nelson, I know you have myriad systems available.  I just didn't
want to add to your burden by asking for quick rebuilds, which usually
ends up being needed at some point.  I'm also not sure about
dependencies.  If you have time, we could discuss.