Added failing test for int64 parsing

It looks like parsing an ERANGE integer results in all consecutive
parses failing with an ERANGE.
Fixed a bug in parsing 64 bit integers

Return value errno == ERANGE is a bit tricky, because its 1)
non-standard and 2) it does NOT get reset across multiple calls. So once
we get an ERANGE error all consecutive parses will fail with an ERANGE.