* Fixes a non-deterministic polarity error for $eqx/$nex cells
* Fixes a deterministic polarity error for $_NOR_ and $_ORNOT_ cells
* Generates hdlnames when xprop is run after flatten
This adds the xprop_decoder attribute to bwmuxes that drive the original
unencoded signals. Setundef is changed to ignore the x inputs of these
bwmuxes, so that they survive the prep script of SBY's formal flow. This
is required to make simulation (via sim) using the prep model show the
decoded x signals instead of 0/1 values made up by the solver.
Jannis Harder