ntdll: Fix NtAccessCheck for NULL, but present SACLs and DACLs.

[Juan Lang]

Hi Rob,

-        sd.sacl_len = (present ? sacl->AclSize : 0);
+        sd.sacl_len = ((present && dacl) ? sacl->AclSize : 0);

Shouldn't that be ((present && sacl) ? sacl->AclSize : 0); ?
--Juan