Jansson tries to use Windows' CryptoApi to seed its hash table. This API
is not exposed in UWP, but there is still a fallback to use current time
and PID.
This change makes Jansson use less-secure fallback, but fixes
compilation for UWP target.
See
https://jansson.readthedocs.io/en/2.10/apiref.html#c.json_object_seed