Ips stats v1.2

Updated PR #860 with only a change in function name and type.

Redmine tickets: https://redmine.openinfosecfoundation.org/issues/1115

PR builds:
- PR build: https://buildbot.suricata-ids.org/builders/regit/builds/112
- PR pcaps: https://buildbot.suricata-ids.org/builders/regit-pcap/builds/51