mod_http_oauth2: Reject loopback URIs as client_uri This really should be a proper website with info, https://localhost is not good enough. Ideally we'd validate that it's got proper DNS and is actually reachable, but triggering HTTP or even DNS lookups seems like it would carry abuse potential that would best to avoid.

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summary: Log a message once per minute
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This module sends `-- MARK --` to the log once per minute. This may be
useful to give a sense of how busy the server is or see that logging and
timers are still working.