[RFA/win32] move "mappings" array to a 32bit-specific nat file

[Joel Brobecker]

> >2009-01-10  Joel Brobecker  <brobecker@adacore.com>
> >
> >        * win32-nat.h: New file.
> >        * win32-nat.c (mappings): Initialize to NULL.
> >        (win32_set_context_register_offsets): New function.
> >        * i386-windows-nat.c: New file.
> >        (mappings): Moved here from win32-nat.c.
> >        (_initialize_i386_windows_nat): New function.
> >        * config/i386/mingw.mh (NATDEPFILES): Add i386-windows-nat.o.
> >        * config/i386/cygwin.mh (NATDEPFILES): Likewise.
> >
> >Tested on x86-windows.
> >OK to apply?
> 
> This is ok.

Thank you! Now checked in.

-- 
Joel