You must install libopus-dev to build mod_opus
https://blog.csdn.net/quantum7/article/details/104087104
yum install -y opus-devel
export PKG_CONFIG_PATH=/usr/lib64/pkgconfig:/usr/local/lib/pkgconfig:/usr/local/lib64/pkgconfig:${PKG_CONFIG_PATH}
比如freeswitch,modules.conf
codecs/mod_opus