[rtler] use iverilog to test ToVerilog, several tests fail
[rtler] use iverilog to test ToVerilog, several tests fail

Abhinav117/pymtl,12yujim/pymtl,12yujim/pymtl,cfelton/pymtl,jck/pymtl,cornell-brg/pymtl,jjffryan/pymtl,jck/pymtl,Glyfina-Fernando/pymtl,cfelton/pymtl,cornell-brg/pymtl,12yujim/pymtl,tj93/pymtl,cornell-brg/pymtl,tj93/pymtl,jck/pymtl,tj93/pymtl,Abhinav117/pymtl,jjffryan/pymtl,Glyfina-Fernando/pymtl,Abhinav117/pymtl,jjffryan/pymtl,Glyfina-Fernando/pymtl,cfelton/pymtl,Abhinav117/pymtl