Issue #508: `-fPIC` to link libjson-c.a with libs

Issue #508: `-fPIC` to link libjson-c.a with libs

json-c has symbol collisions with other popular C JSON libraries.
To prevent random crashes in downstream applications that may use a
library which depends on json-c, the solution is to statically link
libjson-c.a into those libraries.

`-fPIC`/`-fPIE` is required when building a `.a` so it can be linked
into a `.so`.