Security update for graphite2 (important)

This update for graphite2 fixes the following issues:

• CVE-2016-1521: The directrun function in directmachine.cpp in
  Libgraphite did not validate a certain skip operation, which allowed
  remote attackers to execute arbitrary code, obtain sensitive information,
  or cause a denial of service (out-of-bounds read and application crash)
  via a crafted Graphite smart font.

• CVE-2016-1523: The SillMap::readFace function in FeatureMap.cpp in
  Libgraphite mishandled a return value, which allowed remote attackers to
  cause a denial of service (missing initialization, NULL pointer
  dereference, and application crash) via a crafted Graphite smart font.

• CVE-2016-1526: The TtfUtil:LocaLookup function in TtfUtil.cpp in
  Libgraphite incorrectly validated a size value, which allowed remote
  attackers to obtain sensitive information or cause a denial of service
  (out-of-bounds read and application crash) via a crafted Graphite smart
  font.