improved snapshot for CHICKEN 6 on win32

Hi!

We made some progress with the Win32 build of CHICKEN 6, with the
help of several people (many thanks to "johnjaye" and Anton Idukov!)
on #chicken and reports from the mailing list.

Here is a new snapshot tarball:

  http://www.call-with-current-continuation.org/chicken-6-prelim.tar.gz

If you want to help us, consider giving it a try and report back any
problems you encounter. Please remember that our mingw toolchain
of choice is Chris Wellons' w64devkit[1], so try to use this if possible
to maximize the chance that we can reproduce any issues.


cheers,
felix


[1] https://nullprogram.com/blog/2021/03/11/