Log Message:
expat: update to 2.2.6.

Release 2.2.6 Sun August 12 2018
        Bug fixes:
       #170 #206  Avoid doing arithmetic with NULL pointers in XML_GetBuffer
       #204 #205  Fix 2.2.5 regression with suspend-resume while parsing
                    a document like '<root/>'

        Other changes:
       #165 #168  Autotools: Fix docbook-related configure syntax error
            #166  Autotools: Avoid grep option `-q` for Solaris
            #167  Autotools: Support
                    ./configure DOCBOOK_TO_MAN="xmlto man \ 
--skip-validation"
       #159 #167  Autotools: Support DOCBOOK_TO_MAN command which produces
                    xmlwf.1 rather than XMLWF.1; also covers case insensitive
                    file systems
            #181  Autotools: Drop -rpath option passed to libtool
            #188  Autotools: Detect and deny SGML docbook2man as ours is XML
            #188  Autotools/CMake: Support command db2x_docbook2man as well
            #174  CMake: Introduce option WARNINGS_AS_ERRORS, defaults to OFF
       #184 #185  CMake: Introduce option MSVC_USE_STATIC_CRT, defaults to OFF
       #207 #208  CMake: Introduce option XML_UNICODE and XML_UNICODE_WCHAR_T,
                    both defaulting to OFF
            #175  CMake: Prefer check_symbol_exists over check_function_exists
            #176  CMake: Create the same pkg-config file as with GNU Autotools
       #178 #179  CMake: Use GNUInstallDirs module to set proper defaults for
                    install directories
            #208  CMake: Utilize expat_config.h.cmake for XML_DEV_URANDOM
            #180  Windows: Fix compilation of test suite for Visual Studio 2008
  #131 #173 #202  Address compiler warnings
  #187 #190 #200  Fix miscellaneous typos
                  Version info bumped from 7:7:6 to 7:8:6

Release 2.2.5 Tue October 31 2017
        Bug fixes:
              #8  If the parser runs out of memory, make sure its internal
                    state reflects the memory it actually has, not the memory
                    it wanted to have.
             #11  The default handler wasn't being called when it should for
                    a SYSTEM or PUBLIC doctype if an entity declaration handler
                    was registered.
       #137 #138  Fix a case of mistakenly reported parsing success where
                    XML_StopParser was called from an element handler
            #162  Function XML_ErrorString was returning NULL rather than
                    a message for code XML_ERROR_INVALID_ARGUMENT
                    introduced with release 2.2.1

        Other changes:
            #106  xmlwf: Add argument -N adding notation declarations
        #75 #106  Test suite: Resolve expected failure cases where xmlwf
                    output was incomplete
            #127  Windows: Fix test suite compilation
       #126 #127  Windows: Fix compilation for Visual Studio 2012
                  Windows: Upgrade shipped project files to Visual Studio 2017
        #33 #132  tests: Mass-fix compilation for XML_UNICODE_WCHAR_T
            #129  examples: Fix compilation for XML_UNICODE_WCHAR_T
            #130  benchmark: Fix compilation for XML_UNICODE_WCHAR_T
            #144  xmlwf: Fix compilation for XML_UNICODE_WCHAR_T; still needs
                    Windows or MinGW for 2-byte wchar_t
              #9  Address two Clang Static Analyzer false positives
             #59  Resolve troublesome macros hiding parser struct membership
                    and dereferencing that pointer
              #6  Resolve superfluous internal malloc/realloc switch
       #153 #155  Improve docbook2x-man detection
            #160  Undefine NDEBUG in the test suite (rather than rejecting it)
            #161  Address compiler warnings
                  Version info bumped from 7:6:6 to 7:7:6