ofproto-dpif: Honor statistics in packet_out().

ofproto-dpif: Honor statistics in packet_out().

A "packet out" ordinarily isn't accounted to any OpenFlow rule,
because its actions come directly from the controller instead of
from an OpenFlow rule.  However, any "resubmit" actions or output
to OFPP_TABLE within the set of actions do bring in actions from a
rule, and the "packet out" should be accounted to the rule in that
case.  This commit implements that behavior.

Reported-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: Ethan Jackson <ethan@nicira.com>