lib: use differing NTSTATUS and WERROR struct members

lib: use differing NTSTATUS and WERROR struct members

This allows the compiler to catch uses of incorrectly typed arguments
for [NT_STATUS|W_ERROR]_IS_OK() and [NT_STATUS|W_ERROR]_EQUAL(). I.e.

WERROR werr;

werr = my_fn();        /* XXX returns WERROR type */

if (NT_STATUS_EQUAL(werr, NT_STATUS_OBJECT_NAME_COLLISION)) {