Thanks to NaGa for Status Monitor Pro!
Horizon-OC-Monitor is deprecated. If you want to compile it anyway, create a lib folder and clone Atmosphere-libs and libultrahand into it:
mkdir lib
git clone https://github.com/Atmosphere-NX/Atmosphere-libs lib/Atmosphere-libs
git clone https://github.com/ppkantorski/libultrahand lib/libultrahand