RFR(S): 8209691: Allow MemBar on single memory slice

[Roland Westrelin]

> Looks good.
>
> +    !strcmp(_opType,"MemBarStoreStore") ||
> +    !strcmp(_opType, "OnSpinWait");
>                       ^ remove this space

Thanks for the review. I'll remove the space. Anyone else for a review?

Roland.