Make unittest independent from the location of the executable.
Summary:
This fixes the check in the unittest when doing
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/bin")
which I intend to do globally at some point.
Turns out it's comparing with its own executable location, so we
can use QCoreApplication to get it generically.
Test Plan: Verified to work with ctest and with "./testWaylandServerDisplay"
Reviewers: graesslin, mart
Reviewed By: graesslin, mart
Subscribers: plasma-devel, Frameworks
Tags: Plasma on Wayland, Frameworks
Differential Revision: https://phabricator.kde.org/D6974