Fix the MS-Windows build: now guile.c must always be compiled in.

* build_w32.bat: Always compile guile.c and link against guile.o.
  Reported by Alexey Pavlov <alexpux@gmail.com>.

* makeint.h (guile_gmake_setup): Define prototype unconditionally,
to avoid compiler warnings.
Fix SV bug #40227 with respect to stack size set for the MSVC build.

* NMakefile.template (/STACK): Increase to 0x400000, mainly for
the 64-bit builds.  Fixes SV bug #40227.
Copyright-paperwork-exempt: Yes.
(guile): Uncomment.