windows: correct GetStdHandle definition

GetStdHandle: https://msdn.microsoft.com/en-us/library/windows/desktop/ms683231(v=vs.85).aspx
DWORD: https://msdn.microsoft.com/en-us/library/windows/desktop/aa383751(v=vs.85).aspx

Change-Id: I2fb794f85418e7846687911c4513886eb1803770
Reviewed-on: https://go-review.googlesource.com/39608
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/windows/zsyscall_windows.go b/windows/zsyscall_windows.go
index 1e27d81..0797ad0 100644
--- a/windows/zsyscall_windows.go
+++ b/windows/zsyscall_windows.go
@@ -620,7 +620,7 @@
 	return
 }
 
-func GetStdHandle(stdhandle int) (handle Handle, err error) {
+func GetStdHandle(stdhandle uint32) (handle Handle, err error) {
 	r0, _, e1 := syscall.Syscall(procGetStdHandle.Addr(), 1, uintptr(stdhandle), 0, 0)
 	handle = Handle(r0)
 	if handle == InvalidHandle {