Allow the Simulator to handle back-to-back signaling from TestIssuer

Allow the Simulator to handle back-to-back signaling from TestIssuer

TestIssuer can signal the end of an instruction and, after skipping mask
bits, signal the end of the VL loop, right on the following cycle.
Since there is no handshake between TestIssuer and Simulator, we need to
remove any wait state that would cause the Simulator to miss the one-clock
pulse.