internal/syscall/windows: increase internal Windows O_ flags values
The lowercase o_ flags are invented values. These conflict with
constants that will soon be allowed by os.OpenFile, which values will
be mandated by the Windows API. To avoid this overlap, the internal
values have been increased to the 33-63 bit range, as the Windows ones
are in the 0-32 bit range.
Updates #73676
Change-Id: I0f657f3ed3403de150f1730a5a65ae887a18a4e9
Reviewed-on: https://go-review.googlesource.com/c/go/+/697363 Reviewed-by: Damien Neil <dneil@google.com> Reviewed-by: Carlos Amedee <carlos@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>