json-c: upgrade to 0.13.1
* from https://github.com/json-c/json-c/commit/
861c1a82868831bf82222f974f05c2af5a975d12
* Bump the major version of the .so library generated up to 4.0 to avoid
conflicts because some downstream packagers of json-c had already done
their own bump to ".so.3" for a much older 0.12 release.
* Add const size_t json_c_object_sizeof()
* Avoid invalid free (and thus a segfault) when ref_count gets < 0
* PR#394: fix handling of custom double formats that include a ".0"
* Avoid uninitialized variable warnings in json_object_object_foreach
* Issue #396: fix build for certain uClibc based systems.
* Add a top level fuzz directory for fuzzers run by OSS-Fuzz
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
