syscall: restore broken GetQueuedCompletionStatus signature but make it not crash

This reverts commit dc4698f5, and then
fixes the memory corruption issue. It also suggests users switch to
x/sys/windows for the proper function.

This requires CL 295174 to be submitted first.

Updates #44538.

Change-Id: I0ee602f1c1d6a89cc585aff426833a4cb3f2be50
Reviewed-on: https://go-review.googlesource.com/c/go/+/296149


Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Trust: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>