xerces-c: update to 3.2.1.

Release Notes - Xerces-C++ - Version 3.2.1

** Bug
    * [XERCESC-2114] - Link failure with Xalan-C
    * [XERCESC-2119] - warning C4251: 'xercesc_3_2::TranscodeToStr::fString': class 'xercesc_3_2::ArrayJanitor<XMLByte>' needs to have dll-interface to be used by clients of class 'xercesc_3_2::TranscodeToStr'
    * [XERCESC-2121] - xercesc-3.2.0 fails to configure with cmake, gnuiconv on Solaris.
    * [XERCESC-2122] - CMake: wrong substitutions in pkg-config file
    * [XERCESC-2123] - Tests sometimes fail when run in parallel, due to race conditions
    * [XERCESC-2124] - Typo in XMLUni::fgDOMDisallowDoctype XMLCh array
    * [XERCESC-2125] - CMake variable for nothreads does not match generated config define
    * [XERCESC-2130] - UTF16 Surrgate values 0xD800-0xDFFF can not longer be written with xerces 3.2.0 (e.g. emoticons)
    * [XERCESC-2137] - CMake Build Doesn't Activate XERCES_MFC_SUPPORT

** Improvement
    * [XERCESC-2132] - cmake: Add the ability to force the specific XMLCh type to use
    * [XERCESC-2134] - Remove non-functional Win32MsgLoader code
    * [XERCESC-2136] - Add support for versioning sources and documentation automatically

(wiz)