actually initialize kcrash for xclipboardsync

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.

https://markmail.org/thread/zv5pheijaze72bzs

Test Plan: builds; correctly links kcrash

Reviewers: davidedmundson

Reviewed By: davidedmundson

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D16923