accept a second number for TCP_CWND

pivoting to 99 to make future maintenance simpler.
Add TCP_FASTLY_INFO, export nexthop used.

Conflicts:
	net/ipv4/tcp.c
Revert "ipv4: fix race in concurrent ip_route_input_slow()"

This reverts commit dcdfdf56b4a6c9437fc37dbc9cee94a788f9b0c4.