Retiring setup.hint

[Jon Turney]

I propose that calm will stop accepting uploads containing setup.hint 
some time shortly after 2017-11-18.

This is approximately one year after the cygport release [1] which, 
stopped generating these files, so if you're using cygport >= 0.23.0, no 
action is needed.

Warnings that you need to upgrade cygport have been generated for more 
than 6 months [2].

After setup.hint uploads are disabled, any remaining setup.hint in the 
cygwin release on sourceware.org will be migrated to pvr.hint(s), as per 
[3].

[1] https://cygwin.com/ml/cygwin-announce/2016-11/msg00078.html
[2] https://cygwin.com/ml/cygwin-apps/2017-04/msg00024.html
[3] https://cygwin.com/ml/cygwin-apps/2016-09/msg00025.html