Summary:
Using the DBus API directly is done in both powerdevil and kscreen ATM.
Leaving the time dataengine the odd one out. It's also not used on Linux
where we use the more appropriate kernel signal, so linking a dead library is
extra pointless

Test Plan: Tested compile by altering some #ifdefs

Reviewers: #plasma

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D11966