By Kole Casule SKOPJE (Reuters) - Austria told Macedonia on Friday to be ready to "completely stop" the flow of migrants across its southern border from Greece and said it would do the same on its own frontiers within months. Macedonia has erected two lines of metal fencing topped with razor wire along the border at the main crossing point from Greece for migrants, many of them Syrian refugees, crossing the Balkan peninsula en route to western Europe. Austria, which received 90,000 asylum requests last year, has set a limit of less than half that number for this year.