fix system module build check
fix system module build check

alexisvincent/builder,lookfirst/builder,jrauschenbusch/builder,whitneyit/builder,whitneyit/builder,systemjs/builder,douglasduteil/builder,douglasduteil/builder,alexisvincent/builder,jrauschenbusch/builder,lookfirst/builder,systemjs/builder,systemjs/builder,alexisvincent/builder,jrauschenbusch/builder