dpif: Wildcard bond output port with recirculation

This patch took advantage of the recirculation infrastructure
introduced in commit adcf00ba35a0, allowing megaflows to be generated
when the flow output to bond ports.

Without recirculation, it is necessary flows output to Bond ports
in balance_tcp mode to unmask all hash fields. With recirculation,
masking of hash fields is no longer required as kernel
now hashes each packet and redirects packets based on the hash value
using recirculation.

This patch removes the masking requirements when recirculation is
in use. Datapaths do not support recirculation are still supported,
but without the benefits of megaflow.

Signed-off-by: Andy Zhou <azhou@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
ofproto-macros.at: Assert daemon commands creates pidfile before exiting

I observed that "ofproto-dpif - ofproto-dpif-monitor 2" test,
which merely accesses ovsdb, failed in OVS_VSWITCHD_STOP's
"ovs-appctl -t ovs-vswitchd exit".  This commit tries to catch
the problem earlier by sprinkling AT_CHECKs.
netdev-bsd: Update for recent ofpbuf api changes

Leftovers from commit commit 1f317cb5.
("ofpbuf: Introduce access api for base, data and size.")

This fixes regressons introduced by commit 3f976e12.
("lib/ofpbuf: Rename private fields to discourage direct use.")