pn: also split off wires on reuse dependences

pn: also split off wires on reuse dependences

Before this patch, no wires would be extracted from reuse dependences,
because we kept track of the original access that gave rise to the
dependence in control_from_access and used that in set_local_control_name
to refer to this access instead of the from_access of the dependence.

Later, we will be performing multiple assignment handling after
reuse detection on the data channels and this may result in data
both getting propagated from a previous iteration of the sink and
coming in from the source.  The control information determines which
of the two is valid.  Since ports domains are only allowed to depend
controls that correspond to the edge that the ports are attached to,
we need to introduce a wire/gate so that only the correct data is used.

Since we no longer use control_from_access in set_local_control_name,
there is also no reason anymore to set this field in add_reuse.

Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>