[SECURITY] Fedora 26 Update: libextractor-1.6-2.fc26

libextractor is a simple library for keyword extraction. libextractor does not support all formats but supports a simple plugging mechanism such that you can quickly add extractors for additional formats, even without recompiling libextractor. libextractor typically ships with a dozen helper-libraries that can be used to obtain keywords from common file-types. libextractor is a part of the GNU project (http://www.gnu.org/).