Log Message:
Update tor to 0.2.6.8. From Christian Sturm in PR pkg/49917.

Changes in version 0.2.6.8 - 2015-05-21
  Tor 0.2.6.8 fixes a bit of dodgy code in parsing INTRODUCE2 cells, and
  fixes an authority-side bug in assigning the HSDir flag. All directory
  authorities should upgrade.

  o Major bugfixes (hidden services, backport from 0.2.7.1-alpha):
    - Revert commit that made directory authorities assign the HSDir
      flag to relay without a DirPort; this was bad because such relays
      can't handle BEGIN_DIR cells. Fixes bug 15850; bugfix
      on tor-0.2.6.3-alpha.

  o Minor bugfixes (hidden service, backport from 0.2.7.1-alpha):
    - Fix an out-of-bounds read when parsing invalid INTRODUCE2 cells on
      a client authorized hidden service. Fixes bug 15823; bugfix
      on 0.2.1.6-alpha.

  o Minor features (geoip):
    - Update geoip to the April 8 2015 Maxmind GeoLite2 Country database.
    - Update geoip6 to the April 8 2015 Maxmind GeoLite2
      Country database.

Changes in version 0.2.6.7 - 2015-04-06
  Tor 0.2.6.7 fixes two security issues that could be used by an
  attacker to crash hidden services, or crash clients visiting hidden
  services. Hidden services should upgrade as soon as possible; clients
  should upgrade whenever packages become available.

  This release also contains two simple improvements to make hidden
  services a bit less vulnerable to denial-of-service attacks.

  o Major bugfixes (security, hidden service):
    - Fix an issue that would allow a malicious client to trigger an
      assertion failure and halt a hidden service. Fixes bug 15600;
      bugfix on 0.2.1.6-alpha. Reported by "disgleirio".
    - Fix a bug that could cause a client to crash with an assertion
      failure when parsing a malformed hidden service descriptor. Fixes
      bug 15601; bugfix on 0.2.1.5-alpha. Found by "DonnchaC".

  o Minor features (DoS-resistance, hidden service):
    - Introduction points no longer allow multiple INTRODUCE1 cells to
      arrive on the same circuit. This should make it more expensive for
      attackers to overwhelm hidden services with introductions.
      Resolves ticket 15515.
    - Decrease the amount of reattempts that a hidden service performs
      when its rendezvous circuits fail. This reduces the computational
      cost for running a hidden service under heavy load. Resolves
      ticket 11447.