This adds support for BBR (Bottleneck Bandwidth and RTT) TCP
congestion control. Applications (e.g. webservers, VPN client/server)
which initiate connections from router side can benefit from this.
This provide an easier way for users to use BBR by selecting /
installing kmod-tcp-bbr instead of altering kernel config and
compiling firmware by themselves.
Signed-off-by: Keith Wong <keithwky@gmail.com>