Log Message:
libxml2: update to 2.9.14, includes security fixes

v2.9.14: May 02 2022:
   - Security:
  [CVE-2022-29824] Integer overflow in xmlBuf and xmlBuffer
  Fix potential double-free in xmlXPtrStringRangeFunction
  Fix memory leak in xmlFindCharEncodingHandler
  Normalize XPath strings in-place
  Prevent integer-overflow in htmlSkipBlankChars() and xmlSkipBlankChars()
    (David Kilzer)
  Fix leak of xmlElementContent (David Kilzer)

   - Bug fixes:
  Fix parsing of subtracted regex character classes
  Fix recursion check in xinclude.c
  Reset last error in xmlCleanupGlobals
  Fix certain combinations of regex range quantifiers
  Fix range quantifier on subregex

   - Improvements:
  Fix recovery from invalid HTML start tags

   - Build system, portability:
  Define LFS macros before including system headers
  Initialize XPath floating-point globals
  configure: check for icu DEFS (James Hilliard)
  configure.ac: produce tar.xz only (GNOME policy) (David Seifert)
  CMakeLists.txt: Fix LIBXML_VERSION_NUMBER
  Fix build with older Python versions
  Fix --without-valid build