[tlbuild] tl24 pretest builds

[Karl Berry]

I've committed the initial set of tl24 binaries, autobuilt from github
and contextgarden, and made the other usual changes.

Remaining platforms:
  windows - for Akira.
  *netbsd -- for Marc.
  cygwin  -- for Ken.
  darwin -- for Dick.
  armhf-linux -- the autobuild failed on both github and cg.
    Until that is resolved, Simon, can you please build it :)?

Feel free to commit to trunk or send me urls as usual.

I'll announce it on the tex-live list tomorrow, after there's a chance
for more binaries. --thanks, karl.