jsonapi: Use size_t
Use size_t instead of int for object sizes in the jsonapi. This makes
the API better self-documenting.
Reviewed-by: Andrew Dunstan <andrew@dunslane.net>
Discussion: https://www.postgresql.org/message-id/flat/
f732b014-f614-4600-a437-
dba5a2c3738b%40eisentraut.org