Two types of non-inverting 2-way muxes. The <B>v0</B> muxes
are minimum width but slow on pin <SPAN CLASS="boldred">s</SPAN>
as the inverting path to pin <SPAN CLASS="boldred">z</SPAN>
has three stage delays. The <B>v2</B> mux uses transfer gates for
the best speed but is bigger.
