openvswitch: FTBFS with dpkg-buildpackage.

openvswitch: FTBFS with dpkg-buildpackage.

The debian packages are ready. This patch fixes the
bug #831924 reported at debian bug tracking system.
With this patch, openvswitch-2.6.1 will be upload to
the Debian archive.  If we build the packages with
"dpkg-buildpackage --target binary-indep", an error
state arises. debian/rules should be modified so that
the build-indep and binary-indep target generates
the architecture independent packages. If there are
things not be handled properly，let me know.

Reported-at: https://people.debian.org/~lucas/logs/2016/07/20/openvswitch_2.5.1~pre+git20160626-2_unstable_archallonly.log
Signed-off-by: nickcooper-zhangtonghao <nic@opencloud.tech>
Signed-off-by: Ben Pfaff <blp@ovn.org>