CMake Error at add_library.cmake:2 \(add_library\): Error evaluating generator expression: \$ \$ may only be used with binary targets to specify include directories, compile definitions, and compile options. It may not be used with the add_custom_command, add_custom_target, or file\(GENERATE\) commands. Call Stack \(most recent call first\): CMakeLists.txt:3 \(include\)