actually initialize kcrash properly

Summary:
to successfully use kcrash when linking with as-needed (which is a default
flag on many linux distros) one also needs to call KCrash::initialize.

without this kcrash may not be available for most users.

https://markmail.org/thread/zv5pheijaze72bzs

Test Plan: builds; extractor links to kcrash as expected

Reviewers: Baloo, Frameworks, apol

Reviewed By: apol

Subscribers: kde-frameworks-devel

Tags: Frameworks, Baloo

Differential Revision: https://phabricator.kde.org/D17019