Predicate Make :: lastRefRedefExt
NB: If this predicate is exposed, it should be cached.
Holds if the node at index
bb is a last reference to SSA definition
def. The reference is last because it can reach another write
without passing through another read or write.
predicate lastRefRedefExt ( DefinitionExt def , SourceVariable v , BasicBlock bb , int i , DefinitionExt next )