Raspberry Pi 4 install ffpmeg: mmal not found

Recently I use my raspberry Pi 4 and install ffmpeg-4.2.3. When I run ./configure --enable-shared --prefix=$PWD/_install --enable-gpl --enable-libx264 --enable-omx-rpi --enable-mmal --enable-hwaccel=h264_mmal --enable-decoder=h264_mmal --enable-encoder=h264_omx --enable-omx ,I get the follow error : ERROR: mmal not found,How can fix this .