xc2par: Make ZIA assigning only require macrocell placements
xc2par: Make ZIA assigning only require macrocell placements

It now no longer requires product-term placements. This is possible
because every ZIA choice is available to be used in every product term.
This is useful because it allows both types of "badness" scores to be
calculated and combined together.

azonenberg/openfpga,azonenberg/openfpga,rqou/openfpga,rqou/openfpga,rqou/openfpga,azonenberg/openfpga,rqou/openfpga,azonenberg/openfpga,azonenberg/openfpga,rqou/openfpga