[PATCH 2/2] ntdll/tests: Add tests for RtlEncode(System)Pointer.

[Myah Caron]

> It turns out that newer Windows versions rotate the cookie and the pointer right by an amount specified by the
> first 31/63 bits before XORing them.

... by an amount specified by the *first 5/6 bits (&31/&63, modulo 32/64)