CL 24551 introduced //go:uintptrescapes comment to make
syscall.Proc.Call and syscall.LazyProc.Call parameters escape.
Use new comment in this package too.

Updates golang/go#16035.

Change-Id: I57ec3b4778195ca4a1ce9a8eec331f0f69285926
Reviewed-on: https://go-review.googlesource.com/24870Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>