libxml2 security update

[2.7.6-12.0.1.el6_4.1]

• Update doc/redhat.gif in tarball
• Add libxml2-oracle-enterprise.patch and update logos in tarball
  [2.7.6-12.el6_4.1]
  -detect and stop excessive entities expansion upon replacement (rhbz#912574)
  [2.7.6-12.el6]
• fix out of range heap access (CVE-2012-5134)
  [2.7.6-11.el6]
• Change the XPath code to percolate allocation error (CVE-2011-1944)
  [2.7.6-10.el6]
• Fix an off by one pointer access (CVE-2011-3102)
  [2.7.6-9.el6]
• Fix a failure to report xmlreader parsing failures
• Fix parser local buffers size problems (rhbz#843742)
• Fix entities local buffers size problems (rhbz#843742)
• Fix an error in previous commit (rhbz#843742)
• Do not fetch external parsed entities
• Impose a reasonable limit on attribute size (rhbz#843742)
• Impose a reasonable limit on comment size (rhbz#843742)
• Impose a reasonable limit on PI size (rhbz#843742)
• Cleanups and new limit APIs for dictionaries (rhbz#843742)
• Introduce some default parser limits (rhbz#843742)
• Implement some default limits in the XPath module
• Fixup limits parser (rhbz#843742)
• Enforce XML_PARSER_EOF state handling through the parser
• Avoid quadratic behaviour in some push parsing cases (rhbz#843742)
• More avoid quadratic behaviour (rhbz#843742)
• Strengthen behaviour of the push parser in problematic situations (rhbz#843742)
• More fixups on the push parser behaviour (rhbz#843742)
• Fix a segfault on XSD validation on pattern error
• Fix an unimplemented part in RNG value validation