/usr/lib/x86_64-linux-gnu/pkgconfig/json.pc is in libjson0-dev 0.11-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/pkgconfig/json-c.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/json-c.pc