libexpat (libbsdxml): Upgrade from version 2.0.1 to 2.1.0

libexpat (libbsdxml): Upgrade from version 2.0.1 to 2.1.0

This is a security update.  Bug fixes since Release 2.0.1:
  #1742315: Harmful XML_ParserCreateNS suggestion.
  #2895533: CVE-2012-1147 - Resource leak in readfilemap.c.
  #1785430: Expat build fails on linux-amd64 with gcc version>=4.1 -O3.
  #1983953, 2517952, 2517962, 2649838:
            Build modifications using autoreconf instead of buildconf.sh.
  #2815947, #2884086: OBJEXT and EXEEXT support while building.
  #1990430: CVE-2009-3720 - Parser crash with special UTF-8 sequences.
  #2517938: xmlwf should return non-zero exit status if not well-formed.
  #2517946: Wrong statement about XMLDecl in xmlwf.1 and xmlwf.sgml.
  #2855609: Dangling positionPtr after error.
  #2894085: CVE-2009-3560 - Buffer over-read and crash in big2_toUtf8().
  #2958794: CVE-2012-1148 - Memory leak in poolGrow.
  #2990652: CMake support.
  #3010819: UNEXPECTED_STATE with a trailing "%" in entity value.
  #3206497: Unitialized memory returned from XML_Parse.
  #3287849: make check fails on mingw-w64.
  #3496608: CVE-2012-0876 - Hash DOS attack.

New Features / API changes:
  Added new API member XML_SetHashSalt() that allows setting an intial
    value (salt) for hash calculations. This is part of the fix for
    bug #3496608 to randomize hash parameters.
  When compiled with XML_ATTR_INFO defined, adds new API member
    XML_GetAttributeInfo() that allows retrieving the byte
    offsets for attribute names and values (patch #3446384).
  Added CMake build system.
    See bug #2990652 and patch #3312568.
  Added run-benchmark target to Makefile.in - relies on testdata module
    present in the same relative location as in the repository.