cmake: fix installation of python extra code

modules/python/common.cmake

@@ -232,8 +232,9 @@ if(NOT OPENCV_SKIP_PYTHON_LOADER)
       if(extra_py_files)
         list(SORT extra_py_files)
         foreach(f ${extra_py_files})
+          get_filename_component(__dir "${f}" DIRECTORY)
           configure_file("${__base}/${f}" "${__loader_path}/cv2/_extra_py_code/${f}" COPYONLY)
-          install(FILES "${__base}/${f}" DESTINATION "${OPENCV_PYTHON_INSTALL_PATH}/cv2/_extra_py_code/${f}" COMPONENT python)
+          install(FILES "${__base}/${f}" DESTINATION "${OPENCV_PYTHON_INSTALL_PATH}/cv2/_extra_py_code/${__dir}/" COMPONENT python)
         endforeach()
       else()
         message(WARNING "Module ${m} has no .py files in misc/python/package")