fast-log: restore logging of Drop/wDrop

Restore drop print logic. Probably got lost in large refactoring round
introducing log APIs.

Bug #1138. https://redmine.openinfosecfoundation.org/issues/1138

Prscript:
- PR build: https://buildbot.suricata-ids.org/builders/inliniac/builds/234
- PR pcaps: https://buildbot.suricata-ids.org/builders/inliniac-pcap/builds/154