[Patches] clean up Win32 build warning (_PyImport_Fini)

[Guido van Rossum]

> Declare _PyImport_Fini in import.h so that other .c files can see it (cleans
> up a build warning on Win32, and Win64 too, but you guys don't know about that yet
> <wink>).

+1

--Guido van Rossum (home page: http://www.python.org/~guido/)