git repositories for cygwin packaging - please test

[Jon Turney <jon dot turney at dronecode dot org dot uk>]

While a number of maintainers keep their cygwin packaging under some 
sort of version control, there is currently no central collection of 
these repositories.

To remedy this lack, using the same ssh key you use for sftp package 
upload, package maintainers can now also push to git repositories, like so:

git push cygwin@cygwin.com:/git/cygwin-packages/<packagename>

where <packagename> is a package name you are listed as a maintainer for 
in http://cygwin.com/cygwin-pkg-maint.

These repositories are lazily created on the first push.

Since it's intended that these repositories will only contain cygport 
scripts, patches, and other packaging files, and to prevent the 
accidental committing of upstream archives, pushes containing large 
binary files will be rejected.

These repositories are viewable via gitweb at 
https://cygwin.com/git-cygwin-packages/ (URL may be subject to change), 
and should be cloneable via anonymous git/http with the URLs shown there.

Please give this a test, if possible, and report any problems here.