Fix our Windows stat() emulation to handle file sizes > 4GB.

Hack things so that our idea of "struct stat" is equivalent to Windows'
struct __stat64, allowing it to have a wide enough st_size field.

Instead of relying on native stat(), use GetFileInformationByHandle().
This avoids a number of issues with Microsoft's multiple and rather
slipshod emulations of stat().  We still need to jump through hoops
to deal with ERROR_DELETE_PENDING, though :-(

Pull the relevant support code out of dirmod.c and put it into
its own file, win32stat.c.

Still TODO: do we need to do something different with lstat(),
rather than treating it identically to stat()?

Juan José Santamaría Flecha, reviewed by Emil Iggland;
based on prior work by Michael Paquier, Sergey Zubkovsky, and others

Discussion: https://postgr.es/m/1803D792815FC24D871C00D17AE95905CF5099@g01jpexmbkw24
Discussion: https://postgr.es/m/15858-9572469fd3b73263@postgresql.org

configure

@@ -16137,6 +16137,12 @@ esac
  ;;
 esac
 
+  case " $LIBOBJS " in
+  *" win32stat.$ac_objext "* ) ;;
+  *) LIBOBJS="$LIBOBJS win32stat.$ac_objext"
+ ;;
+esac
+
 
 $as_echo "#define HAVE_SYMLINK 1" >>confdefs.h