Compile and link with KCrash

Summary: Enable the KCrash integration (which means drkonqi).

Test Plan:
drkonqi is triggered in case of crash. Tested with the use case
described in https://bugs.kde.org/show_bug.cgi?id=398722.
For some reason the backtrace shown by gdb and drkonqi differ,
though.

Reviewers: asemke

Reviewed By: asemke

Differential Revision: https://phabricator.kde.org/D15551