Patch from Robert Vogelgesang:

Patch from Robert Vogelgesang:
	This patch fixes the link statistics for connections that
	go through multiple IPCP up-down cycles.  Such connections
	happen typically in a setup where pppd is used as a back-end
	by a L2TP daemon, in case the PPP session at the other side
	of the L2TP tunnel reconnects, but the L2TP daemon at that
	side just reuses the old L2TP tunnel instead of creating a
	new one.

	The patch is most important when RADIUS accounting is in use:
	Each IPCP-down initiates a RADIUS-Accounting-Stop packet, which
	indicates the end of a session.  Without this patch, the
	accounting information in each subsequent RADIUS-Accounting-Stop
	packet of the very same connection would contain cumulative
	data since the connection start, but not the data of the last
	"sub-session"; in other words, the accounting data sent to
	the RADIUS server would indicate that the client had used much
	more session time and transfered much more data.
	NOTE: The problem fixed by this patch exists even when the
	radius plugin is not in use; when extracting accounting data
	from the syslog, you can work around the bug, because you
	can see there that the same instance of pppd had multiple
	sessions; you cannot see this in the RADIUS accounting data.

	Furthermore, this patch suppresses duplicate printing/syslogging
	of identical data.