Set the "last data" time to "last ping" time when updating the latter

Set the "last data" time to "last ping" time when updating the latter

This is required because the PING can be received quite a bit earlier
than it is actually handled, for example during "server burst" or other
heavy operations:
So the times won't match and PING-PONG logic would become garbled,
because we test for "last ping > last data" to determine if a PING
already was sent or not.