Merge pull request #1493 in SNORT/snort3 from ~SMINUT/snort3:ips_file_type to master

Merge pull request #1493 in SNORT/snort3 from ~SMINUT/snort3:ips_file_type to master

Squashed commit of the following:

commit 6c2e6330bb957da3783c47a1406ecebb479af7cf
Author: Silviu Minut <sminut@cisco.com>
Date:   Wed Jan 23 09:25:26 2019 -0500

    ips_options: implement FileTypeOption::hash() and FileTypeOption::operator==(), inherited from IpsOption, using the types bitset array, in order to distinguish between different file type options.

    ips_options: change strncmp to plain strcmp per reviewers' comments.