Note [Linting of runRW#]

runRW# has some very special behavior (see Note [runRW magic] in
GHC.CoreToStg.Prep) which CoreLint must accommodate, by allowing
join points in its argument.  For example, this is fine:

    join j x = ...
    in runRW#  (\s. case v of
                       A -> j 3
                       B -> j 4)

Usually those calls to the join point 'j' would not be valid tail calls,
because they occur in a function argument.  But in the case of runRW#
they are fine, because runRW# (\s.e) behaves operationally just like e.
(runRW# is ultimately inlined in GHC.CoreToStg.Prep.)

In the case that the continuation is /not/ a lambda we simply disable this
special behaviour.  For example, this is /not/ fine:

    join j = ...
    in runRW# @r @ty (jump j)