ir_to_mesa: Add support for ir_unop_rcp.

This isn't used at the moment, but will be soon.

src/mesa/shader/ir_to_mesa.cpp

@@ -618,6 +618,9 @@ ir_to_mesa_visitor::visit(ir_expression *ir)
    case ir_unop_sign:
       ir_to_mesa_emit_op1(ir, OPCODE_SSG, result_dst, op[0]);
       break;
+   case ir_unop_rcp:
+      ir_to_mesa_emit_scalar_op1(ir, OPCODE_RCP, result_dst, op[0]);
+      break;
 
    case ir_unop_exp:
       ir_to_mesa_emit_scalar_op1(ir, OPCODE_EXP, result_dst, op[0]);