windows: do not overflow key memory in GetQueuedCompletionStatus

The third argument to GetQueuedCompletionStatus is a pointer to a
uintptr, not a uint32. Users of this functions have therefore been
corrupting their memory every time they used it. Either that memory
corruption was silent (dangerous), or their programs didn't work so they
chose a different API to use.

Updates golang/go#44538.

Change-Id: Ie1f66de11001cf9c8195afaa61f003a86f821a95
Reviewed-on: https://go-review.googlesource.com/c/sys/+/295174
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

Author: zx2c4

windows/syscall_windows.go

@@ -208,9 +208,9 @@ func NewCallbackCDecl(fn interface{}) uintptr {
 //sys	GetSystemTimeAsFileTime(time *Filetime)
 //sys	GetSystemTimePreciseAsFileTime(time *Filetime)
 //sys	GetTimeZoneInformation(tzi *Timezoneinformation) (rc uint32, err error) [failretval==0xffffffff]
-//sys	CreateIoCompletionPort(filehandle Handle, cphandle Handle, key uint32, threadcnt uint32) (handle Handle, err error)
-//sys	GetQueuedCompletionStatus(cphandle Handle, qty *uint32, key *uint32, overlapped **Overlapped, timeout uint32) (err error)
-//sys	PostQueuedCompletionStatus(cphandle Handle, qty uint32, key uint32, overlapped *Overlapped) (err error)
+//sys	CreateIoCompletionPort(filehandle Handle, cphandle Handle, key uintptr, threadcnt uint32) (handle Handle, err error)
+//sys	GetQueuedCompletionStatus(cphandle Handle, qty *uint32, key *uintptr, overlapped **Overlapped, timeout uint32) (err error)
+//sys	PostQueuedCompletionStatus(cphandle Handle, qty uint32, key uintptr, overlapped *Overlapped) (err error)
 //sys	CancelIo(s Handle) (err error)
 //sys	CancelIoEx(s Handle, o *Overlapped) (err error)
 //sys	CreateProcess(appName *uint16, commandLine *uint16, procSecurity *SecurityAttributes, threadSecurity *SecurityAttributes, inheritHandles bool, creationFlags uint32, env *uint16, currentDir *uint16, startupInfo *StartupInfo, outProcInfo *ProcessInformation) (err error) = CreateProcessW