真正解决办法：编译freeswitch错误，You must install libavformat-dev to build mod_av

akefile:1442: *** You must install libavformat-dev to build mod_av。 停止。

./configure \
    --prefix=/usr/local \
    --enable-shared --enable-libx264 --enable-gpl \
    --extra-cflags=-I/usr/include --extra-ldflags=-L/usr/lib64

./bootstrap.sh -j

# 编译libav成功
sudo ldconfig
# 修改freeswitch 编译脚本：
export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:${PKG_CONFIG_PATH}
./configure ...