Update Verilator test-bench so that it works on arm64 Macs

Author: ngernest

protocols/tests/wishbone/.gitignore

@@ -0,0 +1,2 @@
+obj_dir/*
+reqwalker_tb

protocols/tests/wishbone/Makefile

@@ -44,7 +44,8 @@ obj_dir/Vreqwalker__ALL.a: obj_dir/Vreqwalker.cpp
 
 reqwalker_tb: reqwalker.cpp obj_dir/Vreqwalker__ALL.a
 	g++ -I$(VINC) -I obj_dir $(VINC)/verilated.cpp	\
-		$(VINC)/verilated_vcd_c.cpp reqwalker.cpp	\
+		$(VINC)/verilated_vcd_c.cpp			\
+		$(VINC)/verilated_threads.cpp reqwalker.cpp	\
 		obj_dir/Vreqwalker__ALL.a -o reqwalker_tb
 
 .PHONY: clean

protocols/tests/wishbone/reqwalker.cpp

@@ -29,6 +29,9 @@
 #include "verilated.h"
 #include "verilated_vcd_c.h"
 
+// Required by Verilator when not using SystemC
+double sc_time_stamp() { return 0; }
+
 int	tickcount = 0;
 Vreqwalker	*tb;
 VerilatedVcdC	*tfp;