adddebug remove adddebug
Reasons:
flags.make does not exist when the CMake generator that is used is ninja.
If you want to enable debug symbols when building, use "cmake-options -DCMAKE_BUILD_TYPE=Debug".
Other CMake build configurations are e.g. "Release" and "RelWithDebInfo".
I suggest that you use a KDE build framework such as kdesrc-build.