syscall: revert security_windows.go change of CL 201877

syscall: revert security_windows.go change of CL 201877

This CL was verified by running:

	go test -gcflags=all=-d=checkptr=2 internal/syscall/windows

internal/syscall/windows.TestRunAtLowIntegrity uses code in question.

Updates #34972

Change-Id: I434530058e2d41f132e9bf154e8c64c03894e9c4
Reviewed-on: https://go-review.googlesource.com/c/go/+/204117
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>