iproute2: add package for bridge program

iproute2: add package for bridge program

The 'bridge' program has been part of iproute2 for a while, and it was once
declared[1] to the the intended longterm replacement for bridge-utils, but
its features are still mostly distinct[2] from the venerable brctl.

[1] http://lwn.net/Articles/435845/
[2] http://sgros-students.blogspot.com/2013/11/comparison-of-brctl-and-bridge-commands.html

Signed-off-by: Russell Senior <russell@personaltelco.net>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43993 3c298f89-4303-0410-b956-a3cf2f4a3e73