forward-port r9916, and remove another duplicated changelog entry

  o Security fixes:

    - Directory authorities now call routers stable if they have an

      uptime of at least 30 days, even if that's not the median uptime

      in the network. Implements proposal 1xx, suggested by Kevin Bauer

      in the network. Implements proposal 107, suggested by Kevin Bauer

      and Damon McCoy.

  o Major bugfixes:

    - Fix an infinite loop introduced in 0.1.2.7-alpha when we serve

      directory information requested inside Tor connections (i.e. via

      begin_dir cells). It only triggered when the same connection was

      serving other data at the same time. Reported by seeess.

  o Minor features (build):

    - Make autoconf search for libevent and openssl consistently.

    - Update deprecated macros in configure.in

      This should improve client CPU usage by 25-50%.

    - Don't crash if, after a server has been running for a while,

      it can't resolve its hostname.

    - When a client asks us to resolve (not connect to) an address,

      and we have a cached answer, give them the cached answer.

      Previously, we would give them no answer at all.

  o Minor bugfixes:

    - Allow Tor to start when RunAsDaemon is set but no logs are set.