cmake HAS_V4L2 examples

prophesee-ai/openeb hal_psee_plugins/src/boards/v4l2/CMakeLists.txt :14 

target_compile_definitions(metavision_hal_psee_plugin_obj PRIVATE HAS_V4L2)

prophesee-ai/openeb hal_psee_plugins/src/plugin/CMakeLists.txt :15 

target_compile_definitions(hal_plugin_prophesee PRIVATE HAS_V4L2)

prophesee-ai/openeb hal_psee_plugins/src/plugin/CMakeLists.txt :16 

endif(HAS_V4L2)