V3 PATCH: numeric_limits<> support, fix PR/3865

[Paul Koning]

>>>>> "Richard" == Richard Henderson <rth@redhat.com> writes:
 Richard> Anyway, I was thinking about how to define your booleans.
 Richard> Seems like the following would work:

 Richard> bool has_infinity = __builtin_huge_val() / 2 == __builtin_huge_val();

>From the name I would expect __builtin_huge_val() to return a large
finite value, not infinite...

       paul