user32: Add a stub for RegisterTouchWindow.

dlls/user32/user32.spec

@@ -573,6 +573,7 @@
 @ stdcall RegisterShellHookWindow (long)
 @ stdcall RegisterSystemThread(long long)
 @ stdcall RegisterTasklist (long)
+@ stdcall RegisterTouchWindow(long long)
 # @ stub RegisterUserApiHook
 @ stdcall RegisterWindowMessageA(str)
 @ stdcall RegisterWindowMessageW(wstr)

dlls/user32/win.c

@@ -3887,3 +3887,13 @@ LONG_PTR WINAPI SetWindowLongPtrA( HWND hwnd, INT offset, LONG_PTR newval )
 {
     return WIN_SetWindowLong( hwnd, offset, sizeof(LONG_PTR), newval, FALSE );
 }
+
+/*****************************************************************************
+ *              RegisterTouchWindow (USER32.@)
+ */
+BOOL WINAPI RegisterTouchWindow(HWND hwnd, ULONG flags)
+{
+    FIXME("(%p %08x): stub\n", hwnd, flags);
+    SetLastError(ERROR_CALL_NOT_IMPLEMENTED);
+    return FALSE;
+}