x264 not found using pkg-config

错误信息：
ERROR: x264 not found using pkg-config

If you think configure made a mistake, make sure you are using the latest
version from Git. If the latest version fails, report the problem to the
ffmpeg-user@ffmpeg.org mailing list or IRC #ffmpeg on irc.libera.chat.
Include the log file “ffbuild/config.log” produced by configure as this will help
solve the problem.

原因：
PKG_CONFIG_PATH环境变量没有配置。

处理方式：
vi ~/.bash_profile
加上一句。

export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig

source ~/.bash_profile