[lmi] Avoiding PETE's overloaded operator==()

[Greg Chicares]

Calling std::operator==() explicitly seems weird, but is there a
better way to avoid the PETE problem below (revision 4975)?

bool database_entity::operator==(database_entity const& z) const
{
#if 0
// PETE causes an 'ambiguous overload' error for vector 'v0==v1'.
    return
           key_          == z.key_
        && axis_lengths_ == z.axis_lengths_
        && data_values_  == z.data_values_
        && gloss_        == z.gloss_
        ;
#endif // 0
    return
           key_          == z.key_
        && std::operator==(axis_lengths_, z.axis_lengths_)
        && std::operator==(data_values_ , z.data_values_ )
        && gloss_        == z.gloss_
        ;
}