tcp: terminate options with nops
tcp: terminate options with nops

On the one hand, make sure options are terminated with NOPs to avoid
issues with clients that can't parse options that don't end on an u32
boundary. On the other, make sure the padding is rfc compliant. If
options end with EOL the padding should be zeros. The current change
does not use EOL so the padding is NOPs.

Type: improvement

Signed-off-by: Florin Coras <c9715e5cdf0718c2e9b10678757dfb027875eba2@cisco.com>
Change-Id: I608056707ef9658ca90b9c095e84a0689d8000d7

chrisy/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp