Windows 64-bit support:

Windows 64-bit support:

* support for building it in the regular makefiles
* large files support via the _*i64() functions (this should be
  portable to the 32-bit universe too, but quite untested and
  and binary-incompatible, therefore not enabled there)
* three additional test failures in addition to the t/end.t one
  (see README.win32)
* sprintf() on Windows gets %I{32,64,}[xoud] format that parallel
  the ones available from the CRT (needed because Perl uses
  the UVxf macros in both sprintf() *and* in sv_catpvf() et al.)
* add a few 64-bit notes to README.win32

The following general problems were also fixed:

* s/struct stat/Stat_t/g
* Data::Dumper had some naughty 'long' typecasts
* Errno_pm.PL didn't work safe when winsock.h was not in the same
  directory as errno.h
* various tell/seek things were incorrectly prototyped
* squelch ugly looking noise when running tests
* Embed.t wasn't linking in all the libraries
* perl57.dll is now perl58.dll (anticipating 5.8.0-RC1)
* re-enable all the disabled warnings (additional fixes may be
  needed for the warnings uncovered by this)

p4raw-id: //depot/perl@16033