Fix build of knotifications on Mac
Summary:
It seems like it depends on qtmacextras which doesn't have a package yet
Test Plan:
Without this change it get the following error:
CMake Error at CMakeLists.txt:60 (find_package):
Could not find a package configuration file provided by "Qt5MacExtras"
(requested version 5.7.0) with any of the following names:
Qt5MacExtrasConfig.cmake
qt5macextras-config.cmake
Add the installation prefix of "Qt5MacExtras" to CMAKE_PREFIX_PATH or set
"Qt5MacExtras_DIR" to a directory containing one of the above files. If
"Qt5MacExtras" provides a separate development package or SDK, be sure it
has been installed.Reviewers: Craft, kfunk
Reviewed By: Craft, kfunk
Subscribers: kfunk
Differential Revision: https://phabricator.kde.org/D9469