[m-rev.] for post-commit review: add an XXX about a bug in pretty_printer.m

[Julien Fischer]

On Fri, 26 Aug 2022, Zoltan Somogyi wrote:

> By the way, would anyone object to changing ops.m to export not just
> the op_table typeclass, but the predicates implementing its methods
> for the Mercury operators? With those predicates hidden, pretty_printer.m
> needs to do unnecessary work every time it formats a term; those exports,
> and a couple of helper predicates, could fix that.

No objections from me.

Julien.