Call Arity: In "e x", the result of "x" is not shared
in contrast to "e (f x)", where CorePrep will turn it into "let y = f x in e x". So in let f = ... in e (f x) we know that f is called at most once, but in let f = ... in e f we do not know that. Previously Call Arity would assume that in "e x", "x" is evaluated at most once. This rarely would make a difference (the argument "x" is analized with an incoming arity of 0, so no eta-expansion would be done anyways), but of course this should still be fixed. This fixes #11064. Note the corresponding code dmdTransformThunkDmd in DmdAnal.