lldpd 0.7.1

lldpd is a 802.1AB implementation (LLDP). It discovers L2 neighbors
along with some information like hostname, port name, VLAN, etc.

Formula comes with support for launchd, creation of privilege
separation user and group and optional SNMP support.

Closes #17052.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>