Set ssthresh appropriately on RTO. This change was accidentally not ported from the pre modular CC stack.
Set ssthresh appropriately on RTO. This change was accidentally not ported from
the pre modular CC stack.

Sponsored by:	FreeBSD Foundation
Submitted by:	David Hayes <dahayes at swin edu au>
MFC after:	9 weeks
X-MFC with:	r215166

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase