[tlbuild] Biber for x86_64-cygwin

[Karl Berry]

Hi Ken,

    1. To get the current version (biber-2.1) into TL, probably the simplest 
    thing is for me to commit the binary to Master/bin/x86_64-cygwin and to 
    commit the following:

Yes.

    2. What has to be done to get future releases of Biber into TL?  

You should build the binary when Philip asks people to, and he (or you,
or someone) put it on sourceforge, in places like
https://sourceforge.net/projects/biblatex-biber/files/biblatex-biber/2.1/binaries/Cygwin/
(except 2.2, presumably -- doesn't matter either way if you update 2.1).

    Is there a script that pulls from Kime's site that would need to be
    modified?

CTAN grabs the relevant sourceforge dir when Phil makes a release, into
mirror.ctan.org/biblio/biber

Then I import from there into TL.  Yes, my import script (ctan2tds) will
need some trivial modification, but that doesn't matter.  As long as the
binaries are on sourceforge in the first place, they'll end up in TL,
eventually.

best,
karl