confusing message in check_tuple

[jian he]

hi.

in contrib/amcheck/verify_heapam.c, check_tuple
        report_corruption(ctx,
                          psprintf("number of attributes %u exceeds
maximum expected for table %u",
                                   ctx->natts,
                                   RelationGetDescr(ctx->rel)->natts));
i think it should be
        report_corruption(ctx,
                          psprintf("number of attributes %u exceeds
maximum expected for table %u",
                                   ctx->natts,
                                   RelationGetRelid(ctx->rel)));

or we can rephrase it another way, also mentioning
``RelationGetDescr(ctx->rel)->natts``.