Accounting-On and Accounting-Off being sent on a per-BSS basis not per-NAS

[Nick Lowe]

The reason that changes to the design of hostap here are demonstrably
necessary and required is that the current implementation will cause
RADIUS servers that act upon Accounting-On/Accounting-Off to mark
sessions of other BSSes that are being accounted for as being stopped
on receipt. In reality though, they haven't been stopped.

These accounting servers have no concept in their code that the
Called-Station-Id is intended to scope, causing this malfunction -
again, they are applied to sessions that exist for the entire NAS.
Therefore, hostapd must not send them on this basis to interoperate.

Nick