Make sure attributes propagate through security wrappers

Both SSecurityVeNCrypt and SSecurityStack are wrappers around other
security objects, so they need to delegate the properties of those
sub-objects properly.
diff --git a/common/rfb/SSecurityStack.h b/common/rfb/SSecurityStack.h
index c80a3b9..dd743d2 100644
--- a/common/rfb/SSecurityStack.h
+++ b/common/rfb/SSecurityStack.h
@@ -31,6 +31,7 @@
     virtual bool processMsg(SConnection* cc);
     virtual int getType() const { return type; };
     virtual const char* getUserName() const;
+    virtual SConnection::AccessRights getAccessRights() const;
   protected:
     short state;
     SSecurity* state0;