64-bit readiness (the config values are needed for patches that I will
be submitting later today. The changes are as follows:

- add SIZEOF_OFF_T #define's to PC/config.h (it was already in configure.in)

- add SIZEOF_TIME_T #define to PC/config.h and configure
Needed for some buffer overflow checking because sizeof(time_t) is
different on Win64.

- add SIZEOF_FPOS_T #define
Needed for the Win64 large file support implementation.

- add SIZEOF_HKEY in PC/config.h only
Needed for proper Win32 vs. Win64 handling in PC/winreg.c

- #define HAVE_LARGEFILE_SUPPORT for Win64

- typedef long intptr_t; for all Windows except Win64 (which defines it
itself)
This is a new ANSI (I think) type that is useful (and used by me) for
proper handling in msvcrtmodule.c and posixmodule.c

- indent the nested #ifdef's and #defines in PC/config.h
This is *so* much more readable. There cannot be a compiler
compatibilty issue here can there? Perl uses indented #defines and it
compiles with everything.