TCP ssn reuse v0.5

Fix the DEBUG_VALIDATION check in https://github.com/inliniac/suricata/pull/1257

Prscript:
- PR build: https://buildbot.openinfosecfoundation.org/builders/inliniac/builds/92
- PR pcaps: https://buildbot.openinfosecfoundation.org/builders/inliniac-pcap/builds/92