[Stackless] Windows binary installer for 2.6.5 doesn't include stackless include files

[Grant Olson]

I'm in the process of updating a project from python 2.4 to python 2.6.
 I've got a few binary components in visual studio.  When I tried to
build in visual studio, it complained that it couldn't find stackless.h.

I grabbed the source.  I needed to add stackless.h and the 'core'
subdirectory.  After that, I could compile.

Obviously not that big of a deal, and most developers will probably use
the source install anyway, but you may want to add these files into the
windows installer if it's not too much trouble.

-Grant