Updated expat to 2.2.4.

Release 2.2.4 Sat Auguest 19 2017
        Bug fixes:
            #115  Fix copying of partial characters for UTF-8 input

        Other changes:
            #109  Fix "make check" for non-x86 architectures that default
                    to unsigned type char (-128..127 rather than 0..255)
            #109  coverage.sh: Cover -funsigned-char
                  Autotools: Introduce --without-xmlwf argument
            #65  Autotools: Replace handwritten Makefile with GNU Automake
            #43  CMake: Auto-detect high quality entropy extractors, add new
                    option USE_libbsd=ON to use arc4random_buf of libbsd
            #74  CMake: Add -fno-strict-aliasing only where supported
            #114  CMake: Always honor manually set BUILD_* options
            #114  CMake: Compile man page if docbook2x-man is available, only
            #117  Include file tests/xmltest.log.expected in source tarball
                    (required for "make run-xmltest")
            #117  Include (existing) Visual Studio 2013 files in source tarball
                  Improve test suite error output
            #111  Fix some typos in documentation
                  Version info bumped from 7:5:6 to 7:6:6

        Special thanks to:
            Jakub Wilk
            Joe Orton
            Lin Tian
            Rolf Eike Beer

Release 2.2.3 Wed August 2 2017
        Security fixes:
            #82  CVE-2017-11742 -- Windows: Fix DLL hijacking vulnerability
                    using Steve Holme's LoadLibrary wrapper for/of cURL

        Bug fixes:
            #85  Fix a dangling pointer issue related to realloc

        Other changes:
                  Increase code coverage
            #91  Linux: Allow getrandom to fail if nonblocking pool has not
                    yet been initialized and read /dev/urandom then, instead.
                    This is in line with what recent Python does.
            #81  Pre-10.7/Lion macOS: Support entropy from arc4random
            #86  Check that a UTF-16 encoding in an XML declaration has the
                    right endianness
        #4 #5 #7  Recover correctly when some reallocations fail
                  Repair "./configure && make" for systems without any
                    provider of high quality entropy
                    and try reading /dev/urandom on those
                  Ensure that user-defined character encodings have converter
                    functions when they are needed
                  Fix mis-leading description of argument -c in xmlwf.1
                  Rely on macro HAVE_ARC4RANDOM_BUF (rather than __CloudABI__)
                    for CloudABI
            #100  Fix use of SIPHASH_MAIN in siphash.h
            #23  Test suite: Fix memory leaks
                  Version info bumped from 7:4:6 to 7:5:6

        Special thanks to:
            Chanho Park
            Joe Orton
            Pascal Cuoq
            Rhodri James
            Simon McVittie
            Vadim Zeitlin
            Viktor Szakats
                and
            Core Infrastructure Initiative

Release 2.2.2 Wed July 12 2017
        Security fixes:
            #43  Protect against compilation without any source of high
                    quality entropy enabled, e.g. with CMake build system;
                    commit ff0207e6076e9828e536b8d9cd45c9c92069b895
            #60  Windows with _UNICODE:
                    Unintended use of LoadLibraryW with a non-wide string
                    resulted in failure to load advapi32.dll and degradation
                    in quality of used entropy when compiled with _UNICODE for
                    Windows; you can launch existing binaries with
                    EXPAT_ENTROPY_DEBUG=1 in the environment to inspect the
                    quality of entropy used during runtime; commits
                    * 95b95032f907ef1cd17ee7a9a1768010a825d61d
                    * 73a5a2e9c081f49f2d775cf7ced864158b68dc80
  [MOX-006]      Fix non-NULL parser parameter validation in XML_Parse;
                    resulted in NULL dereference, previously;
                    commit ac256dafdffc9622ab0dc2c62fcecb0dfcfa71fe

        Bug fixes:
            #69  Fix improper use of unsigned long long integer literals

        Other changes:
            #73  Start requiring a C99 compiler
            #49  Fix "==" Bashism in configure script
            #50  Fix too eager getrandom detection for Debian GNU/kFreeBSD
            #52    and macOS
            #51  Address lack of stdint.h in Visual Studio 2003 to 2008
            #58  Address compile warnings
            #68  Fix "./buildconf.sh && ./configure" for some versions
                    of Dash for /bin/sh
            #72  CMake: Ease use of Expat in context of a parent project
                    with multiple CMakeLists.txt files
            #72  CMake: Resolve mistaken executable permissions
            #76  Address compile warning with -DNDEBUG (not recommended!)
            #77  Address compile warning about macro redefinition

        Special thanks to:
            Alexander Bluhm
            Ben Boeckel
            Cătălin Răceanu
            Kerin Millar
            László Böszörményi
            S. P. Zeidler
            Segev Finer
            Václav Slavík
            Victor Stinner
            Viktor Szakats
                and
            Radically Open Security

(wiz)