advice on minor cleanups?

[Norman Ramsey]

All,

It appears that `runHscBackendPhase` returns a tuple that include an
element of type `Maybe Linkable` but that in practice is always
`Nothing`.  I'm thinking of removing this element from the tuple,
which would also entail simplifying the type of value constructor
`T_HscBackend` for the `TPhase` type.  Simplifying the code seems like
a good thing, but perhaps there is a reason to leave well enough
alone?  Please advise me.


Norman