Increase maximum number of connection requests in queue for a socket

Summary:
FreeBSD servers limit by default to 128 connections queued per socket.
For higher performance, we can allow more connections.

Ysul reached that limit a few times, and WindRiver twice.

Ref T519.

Test Plan: Deploy on FreeBSD servers

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T519

Differential Revision: https://devcentral.nasqueron.org/D2904