windows: add GetKeyboardLayout & ToUnicodeEx

These are used along with GetForegroundWindow and GetWindowThreadProcessId to determine the current user layout and translate the base key the user has pressed.

windows/syscall_windows.go

@@ -211,6 +211,8 @@ func NewCallbackCDecl(fn interface{}) uintptr {
 //sys	OpenProcess(desiredAccess uint32, inheritHandle bool, processId uint32) (handle Handle, err error)
 //sys	ShellExecute(hwnd Handle, verb *uint16, file *uint16, args *uint16, cwd *uint16, showCmd int32) (err error) [failretval<=32] = shell32.ShellExecuteW
 //sys	GetWindowThreadProcessId(hwnd HWND, pid *uint32) (tid uint32, err error) = user32.GetWindowThreadProcessId
+//sys	GetKeyboardLayout(tid uint32) (hkl Handle, err error) = user32.GetKeyboardLayout
+//sys	ToUnicodeEx(vkey uint32, scancode uint32, keystate *byte, pwszBuff *uint16, cchBuff int32, flags uint32, hkl Handle) (ret int32, err error) = user32.ToUnicodeEx
 //sys	GetShellWindow() (shellWindow HWND) = user32.GetShellWindow
 //sys	MessageBox(hwnd HWND, text *uint16, caption *uint16, boxtype uint32) (ret int32, err error) [failretval==0] = user32.MessageBoxW
 //sys	ExitWindowsEx(flags uint32, reason uint32) (err error) = user32.ExitWindowsEx