Update chat/prosody to 0.9.9.

Security fixes:
- Fix path traversal vulnerability in mod_http_files (CVE-2016-1231)
- Fix use of weak PRNG in generation of dialback secrets (CVE-2016-1232)

Bugs:
- Improve handling of CNAME records in DNS
- Fix traceback when deleting a user in some configurations
- MUC: restrict_room_creation could prevent users from joining rooms
- MUC: fix occasional dropping of iq stanzas sent privately between
  occupants
- Fix a potential memory leak in mod_pep

Additions:
- Add http:list() command to telnet to view active HTTP services
- Simplify IPv4/v6 address selection code for outgoing s2s
- Add support for importing SCRAM hashes from ejabberd

(fhajny)