Release the outer unknown in the proxybuffer test to show that the
last release of the outer unknown doesn't free the proxy buffer.

Release the proxy buffer object on the last release of the proxy's outer
unknown, otherwise memory is leaked for the Ndr implementation of
IRpcProxyBuffer.

Fix up the hand-coded proxies to match the behaviour from the Ndr
implementation.

rpcrt4: Fix copying too much data from the buffer by not taking into account the fact that auth_pad_len has been included in the fragment length.

Protect LPGUID typedef by __LPGUID_DEFINED__ being defined.

Protect LPCLSID and LPFMTID typedefs, IsEqualGUID, IsEqualIID,
IsEqualCLSID, IID_NULL, CLSID_NULL and FMTID_NULL defines by
__IID_DEFINED__ being defined.

PSWIZB_DISABLEDFINISH, followed by another one without those flags
should show the next button again and hide the finish button.