x/sys/windows: add func windows.DisconnectNamedPipe(handle Handle) (err error)

Fixes golang/go#66234

Change-Id: I1e4a94e1ca8c01a29bab18e0bf12238c511fe1c6
Reviewed-on: https://go-review.googlesource.com/c/sys/+/570435
Reviewed-by: Quim Muntal <quimmuntal@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

Author: peter-hoogendijk

windows/syscall_windows.go

@@ -165,6 +165,7 @@ func NewCallbackCDecl(fn interface{}) uintptr {
 //sys	CreateFile(name *uint16, access uint32, mode uint32, sa *SecurityAttributes, createmode uint32, attrs uint32, templatefile Handle) (handle Handle, err error) [failretval==InvalidHandle] = CreateFileW
 //sys	CreateNamedPipe(name *uint16, flags uint32, pipeMode uint32, maxInstances uint32, outSize uint32, inSize uint32, defaultTimeout uint32, sa *SecurityAttributes) (handle Handle, err error)  [failretval==InvalidHandle] = CreateNamedPipeW
 //sys	ConnectNamedPipe(pipe Handle, overlapped *Overlapped) (err error)
+//sys	DisconnectNamedPipe(pipe Handle) (err error)
 //sys	GetNamedPipeInfo(pipe Handle, flags *uint32, outSize *uint32, inSize *uint32, maxInstances *uint32) (err error)
 //sys	GetNamedPipeHandleState(pipe Handle, state *uint32, curInstances *uint32, maxCollectionCount *uint32, collectDataTimeout *uint32, userName *uint16, maxUserNameSize uint32) (err error) = GetNamedPipeHandleStateW
 //sys	SetNamedPipeHandleState(pipe Handle, state *uint32, maxCollectionCount *uint32, collectDataTimeout *uint32) (err error) = SetNamedPipeHandleState