mod_pubsub_serverinfo: Fix check for local domain The module was checking whether a host exists, but this may be misleading if our host is loaded before the host that is being checked. This change makes it check the config. This will provide a false positive in the rare case that the host is defined but not activated/enabled. But we don't have an API currently for "is this host configured and enabled?"

---
labels:
- 'Stage-Alpha'
summary: Implements BOSH pre-bind
...

For why this can be useful, see
https://metajack.im/2009/12/14/fastest-xmpp-sessions-with-http-prebinding/

# To enable this module

Add `"http_prebind"` to `modules_enabled` on an anonymous virtual host.

This only works on anonymous ones for now.