is_predicate_p?

[Robert Dewar]

> Perhaps, but it was the earliest conventions used in GCC to distinguish
> predicates (where the term doesn't have the technical MD file meaning), so
> most follow this "rule".  This is from LISP conventions and RMS was the
> origin of its use.

OK, if this is a well established and well used convention, that's reasonable,
but I still find it odd to use a Hungarian-like convention like this and not
enforce it.