Method buildRightShift

\brief Check that a CPUI_INT_RIGHT respects the lanes then generate lane placeholders For the given lane scheme, check that the RIGHT shift is copying whole lanes to each other. If so, generate the placeholder COPYs that model the shift. \param op is the given CPUI_INT_RIGHT PcodeOp \param outVars is the output placeholders for the RIGHT shift \param numLanes is the number of lanes the shift is s