The dummy_acct is only here to avoid repeating null checks in the send
loop below. This doesn't change the end result if the transaction
completes with no problem. As such, only header and body bytes are
accounted for, as before, ignoring h2 framing overhead and in general
other kinds of frames that belong to the stream.

In other words, the only improvement is that ReqAcct doesn't show a full
delivery when the client hangs up before the end of the transaction.

The split of H2_Send will allow handling of error conditions from the
multiple return statements although at this point there is no change in
this area.