testedid: make sure to use uint consistently

Summary:
It seems like compilation was broken with some configurations, e.g.
https://mail.kde.org/pipermail/plasma-devel/2018-August/087929.html
Fixing the types to be proper should address the issue.

Reviewers: #plasma, apol

Reviewed By: apol

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D14548