aflat doesn't generate rules for pass transistors

[nbingham1]

defproc test(bool a, b, c, x, y)
{
  prs {
    passn(a, b, c)
    x -> y-
  }
}

test t;

$aflat tmp.act 
"t.x"->"t.y"-

[nbingham1]

Perhaps if this is intended, then issue a warning when encountering pass transistors to be expanded instead of failing silently.

[rmanohar]

This has been fixed to replicate the old ACT behavior, but the prs model isn't really right. The real fix in progress is to change the output and then fix the simulator to do the right thing... but the old behavior has been restored now.