Perform the abnormal (late) entries normalization in the DAGify pass.
In this way, we are exploiting the information computed by
`GenericRegionInfo` as close as possible to where it is computed the
first time (in DAGify).
Actualize the unit tests to reflect these changes.
Implement the DAGify pass. This pass, using the results exposed by the
`GenericRegionInfo` analysis, transforms all the retreating edges of
each identified `GenericRegion`, processed in a bottom-up fashion, into
a `goto` edge on the `ScopeGraph`.
Andrea Gussoni