I can't say anything about the Windows build aspects.  Some observations
about the curses/test_curses changes:

* test_curses: I'd be happier to see the 'if' statement as sys.platform
!= 'win32' and (not term or term == 'unknown')  -- easier to read.

* test_curses: does putp() make PDCurses crash, or is it not available?
 If the latter, I'd prefer to see 'if hasattr(curses, "putp"): <putp
test>'.    Same for the tparm() test.

* Given that you include term.h and IRIX included term.h, I wonder if we
should make _cursesmodule.c include term.h on all platforms that have
it, and then fix the resulting breakage claimed by the comment (if any).

* Is setupterm() a no-up on Windows?  Maybe the function just shouldn't
be defined on Windows, then, so that user code can check for the
function's existence.