We have lots of inconsistency at the moment in CMakeLists.txt files. Most
of it is due to kwin being a very old project. This change hopefully fixes
all of it.
Summary: Ensures that we can load the plugin when running only from build dir.
Reviewers: #kwin
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D16762
Basically a simplified fork from kwayland-integration.
We cannot use the idletime plugin from kwayland-integration as it
a) doesn't react on our own qpa plugin name
b) performs blocking roundtrips in the main thread -> freeze
This simplifies by using our internal registry and we don't even check
whether Seat and Idle are announced: we know they are.
Reviewed-By: Bhushan Shah
