tap_set_state macro

This function sets the state of a "state follower" which tracks the state of the TAPs connected to the cable. The state follower is hopefully always in the same state as the actual TAPs in the jtag chain, and will be so if there are no bugs in the tracking logic within that cable driver. All the cable drivers call this function to indicate the state they think the TAPs attached to their cables are in. Because this function can also log transitions, it will be helpful to call this function with every transition that the TAPs being manipulated are expected to traverse, not just end points of a multi-step state path.