Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

Add a test for the listen queue using two test programs,
listen, and connect. The listen program is a simple server that
accepts and closes sockets, until a fixed limit, then sets the listen
queue to 0 and counts how many remaining connections it processes.

The connect program repeatedly opens connections and closes them
serving as the driver for the listen program.

Sponsored by: Limelight Networks