[mpiwg-rma] Zero byte RMA operations

[Balaji, Pavan]

Is it allowed for one to do a zero-byte RMA operation on a window of size 0?  I couldn't find any wording in the standard that disallows this.  If I missed something in the standard, I'd appreciate someone pointing out the page/line number specifying it.

The reason is that checking for this adds an extra branch on some networks, which we are trying to avoid.

Thanks,

  -- Pavan