This adjusts gimple-ranger::update_stmt (which inform the range engine 
that a statement has changed under the covers.  I was calculating the 
statement using a fur_depend class instead of a fur_stmt. (FUR is Fold 
Using Range)

The difference between the 2 is that a fur_depend will reigster any 
relations or dependencies it sees with the oracle and GORI. The problem 
is, update_stmt has no context of where this is being done.  The path 
ranger was performing a simplification, and a relation was being set 
globally even though it should not have been.

THe fix is simple, we're only trying to recalculate the result.. limit 
it to that.

Bootstraps on x86_64-pc-linux-gnu with no regressions.  Pushed.

Andrew