Add a family of knobs to /sys/kernel/ipv4 for controlling the TCP window size:
tcp_wmem_min
tcp_wmem_def
tcp_wmem_max
tcp_rmem_min
tcp_rmem_def
tcp_rmem_max
This six values mirror the sysctl knobs in /proc/sys/net/ipv4/tcp_wmem and
/proc/sys/net/ipv4/tcp_rmem.
Sysfs, unlike sysctl, allows us to set and manage the files' permissions and
owners.
Signed-off-by: Robert Love <rlove@google.com>
