Fix bug 1110 - Same PID for patterns with different CASE flags

Fixes bug 1110 https://redmine.openinfosecfoundation.org/issues/1110 and addresses review comments from PR 842, which this PR replaces. Now using SCMemcasecmp() instead of strncasecmp()

Removes the need for the case_state on patterns in MPM.

    PR build: https://buildbot.suricata-ids.org/builders/ken-tilera/builds/115
    PR pcaps: https://buildbot.suricata-ids.org/builders/ken-tilera-pcap/builds/49







https://buildbot.suricata-ids.org/builders/ken-tilera/builds/115