Disable Chromium's crash handler

Summary:
The crash handler was overriding DrKonqi so we were not getting
DrKonqi when KMail (or any other app using QtWebEngine) crashed.

Test Plan:
`kill -ABRT $(pidof kmail)` opens DrKonqi instead of just making
KMail dump stracktrace to stderr

Reviewers: mlaurent

Reviewed By: mlaurent

Subscribers: kde-pim, mlaurent

Tags: #kde_pim

Differential Revision: https://phabricator.kde.org/D16004