Reserve couters in the tcps struct in preparation
for AccECN, extend the debugging output for TF2
flags, optimize the syncache flags from individual
bits to a codepoint for the specifc ECN handshake.
This is in preparation of AccECN.
No functional chance except for extended debug
output capabilities.
Reviewed By: #transport, rrs
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D34161
3f169c54ab