Fix error in somaxconn Linux tuning recommendations

The Linux tuning recommendations suggest a net.core.somaxconn that is less than net.ipv4.tcp_max_syn_backlog.  This will result in the net.ipv4.tcp_max_syn_backlog value being silently truncated within the TCP stack as it must be less than or equal to net.core.somaxconn.  

See the last paragraph of the 'listen' man page: http://man7.org/linux/man-pages/man2/listen.2.html#NOTES