Improve error message in Trac #8883

The improvement is to report the inferred type in the error message,
as suggested in email on ghc-deves (10 Jun 14).
Comments only explaining the imports for GHC.Integer, GHC.Tuple

See Note [Depend on GHC.Integer]
    Note [Depend on GHC.Tuple]

This came up when Joachim got an unexpected missing-dependency
error when fiddling with Data.Coerce.
White space only
Fix tyConToIfaceDecl (Trac #9190)

There are three bugs here, one serious

 * We were failing to tidy the type arguments in an IfTyConParent
   This is what was causing Trac #9190.

 * toIfaceTcArgs is careful to suppress kind arguments, but there
   was a clone, tidyToIfaceTcArgs in IfaceSyn which didn't.
   Now the latter goes via the former.

 * When pretty-printing a IfaceDecl for an algebraic data type, and
   doing so in Haskell-98 syntax, we were silently assuming that the
   universal type variables of the TyCon and the DataCon were the
   same. But that has not been true for some time. Result: a very
   confusing display.

   Solution: during the conversion to IfaceSyn, take the opportunity
   to make the universal type variables line up exactly.  This is very
   easy to do, makes the pretty-printing easy, and leaves open the future
   possiblity of not serialising the universal type variables of the
   data constructor.
Simplify variable naming in tcDataKindSig

Now that we are very consistent about tidying when converting
to IfaceSyn, we don't need to worry about accidental capture
of the "extra" type variables in tcDataKindSig.  (Previously
we gave them weird names like $a.)

However, it is nicer for the user if we don't gratuitously
re-use an in-scope name, so we take care not to do that
.
Fix a serious, but rare, strictness analyser bug (Trac #9128)

In a special case for trivial RHSs (see DmdAnal.unpackTrivial),
I'd forgotten to include a demand for the RHS itself.
See Note [Remember to demand the function itself].

Thanks to David Terei for guiding me to the bug,
at PLDI in Edinburgh.
Fix Windows build (wibble to fix for Trac #4934)