This PR adds four new configuration options for the HTTP client used by the
json unit.
These are http-root-certs for additional TLS root certificates,
http-user-agent for setting a custom user agent, http-client-addr to specify
a local address to bind to, and http-proxies to add HTTP proxies. The last
option is only available if the socks feature is enabled which it is by
default.
The "rtr" and "rtr-tls" targets both keep a list of changes in order to
process RTR serial queries. Due to a bug in the code, this maximum size
of that list was not limited as intended and keeps growing during runtime.
This change fixes this infinite growth and introduces a new config
parameter to the "rtr" and "rtr-tls" targets named "history-size" that
allows setting the maximum number of updates kept. When not present, it
defaults to 10.
