auto-attach: Initial support for Auto-Attach standard

auto-attach: Initial support for Auto-Attach standard

This commit provides the initial delivery of support for the Auto-Attach
standard to Open vSwitch. This standard describes a compact method of using
IEEE 802.1AB Link Layer Discovery Protocol (LLDP) with a IEEE 802.1aq Shortest
Path Bridging (SPB) network to automatically attach network devices not
supporting IEEE 802.1ah to individual services in a SPB network. Specifically
this commit adds base LLDP support to OVS along with the LLDP extension
required to support Auto-Attach.

The base LLDP code within this commit is adapted from the open source LLDPD
project headed by Vincent Bernat. This base code is augmented with OVS specific
logic which integrates LLDP into OVS and which extends LLDP to support
Auto-Attach. The required build system changes are provided to include this new
Auto-Attach feature.

This is the first of a series of commits. Subsequent commits will be provided
to complete the task of adding Auto-Attach to OVS.

Signed-off-by: Ludovic Beliveau <ludovic.beliveau@windriver.com>
Signed-off-by: Dennis Flynn <drflynn@avaya.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>