借鉴别人的思路，整理，优化后在xcode下调试ffmpeg源码的例子
a xcode project for ffmpeg break point debug, based on ffmpeg 3.4.1 this project is useful if you want to deep into ffmpeg source code.
the code is configured as following:
./configure --enable-debug --disable-doc --enable-ffplay --enable-sdl --disable-audiotoolbox
--disable-cuda --disable-cuvid --disable-d3d11va --disable-dxva2
--disable-libmfx --disable-libnpp --disable-mmal --disable-nvenc
--disable-omx --disable-omx-rpi --disable-vaapi --disable-vda
--disable-vdpau --disable-videotoolbox --disable-asm \