expat: update to 2.4.9.

Release 2.4.9 Tue September 20 2022
        Security fixes:
      #629 #640  CVE-2022-40674 -- Heap use-after-free vulnerability in
                    function doContent. Expected impact is denial of service
                    or potentially arbitrary code execution.

        Bug fixes:
            #634  MinGW: Fix mis-compilation for -D__USE_MINGW_ANSI_STDIO=0
            #614  docs: Fix documentation on effect of switch XML_DTD on
                    symbol visibility in doc/reference.html

        Other changes:
            #638  MinGW: Make fix-xmltest-log.sh drop more Wine bug output
      #596 #625  Autotools: Sync CMake templates with CMake 3.22
            #608  CMake: Migrate from use of CMAKE_*_POSTFIX to
                    dedicated variables EXPAT_*_POSTFIX to stop affecting
                    other projects
      #597 #599  Windows|CMake: Add missing -DXML_STATIC to test runners
                    and fuzzers
      #512 #621  Windows|CMake: Render .def file from a template to fix
                    linking with -DEXPAT_DTD=OFF and/or -DEXPAT_ATTR_INFO=ON
      #611 #621  MinGW|CMake: Apply MSVC .def file when linking
      #622 #624  MinGW|CMake: Sync library name with GNU Autotools,
                    i.e. produce libexpat-1.dll rather than libexpat.dll
                    by default.  Filename libexpat.dll.a is unaffected.
            #632  MinGW|CMake: Set missing variable CMAKE_RC_COMPILER in
                    toolchain file "cmake/mingw-toolchain.cmake" to avoid
                    error "windres: Command not found" on e.g. Ubuntu 20.04
      #597 #627  CMake: Unify inconsistent use of set() and option() in
                    context of public build time options to take need for
                    set(.. FORCE) in projects using Expat by means of
                    add_subdirectory(..) off Expat's users' shoulders
      #626 #641  Stop exporting API symbols when building a static library
            #644  Resolve use of deprecated "fgrep" by "grep -F"
            #620  CMake: Make documentation on variables a bit more consistent
            #636  CMake: Drop leading whitespace from a #cmakedefine line in
                    file expat_config.h.cmake
            #594  xmlwf: Fix harmless variable mix-up in function nsattcmp
  #592 #593 #610  Address Cppcheck warnings
            #643  Address Clang 15 compiler warnings
      #642 #644  Version info bumped from 9:8:8 to 9:9:8;
                    see https://verbump.de/ for what these numbers do

        Infrastructure:
      #597 #598  CI: Windows: Start covering MSVC 2022
            #619  CI: macOS: Migrate off deprecated macOS 10.15
            #632  CI: Linux: Make migration off deprecated Ubuntu 18.04 work
            #643  CI: Upgrade Clang from 14 to 15
            #637  apply-clang-format.sh: Add support for BSD find
            #633  coverage.sh: Exclude MinGW headers
            #635  coverage.sh: Fix name collision for -funsigned-char

        Special thanks to:
            David Faure
            Felix Wilhelm
            Frank Bergmann
            Rhodri James
            Rosen Penev
            Thijs Schreijer
            Vincent Torri
                and
            Google Project Zero

Release 2.4.8 Mon March 28 2022
        Other changes:
            #587  pkg-config: Move "-lm" to section "Libs.private"
            #587  CMake|MSVC: Fix pkg-config section "Libs"
        #55 #582  CMake|macOS: Start using linker arguments
                    "-compatibility_version <version>" and
                    "-current_version <version>" in a way compatible with
                    GNU Libtool
      #590 #591  Version info bumped from 9:7:8 to 9:8:8;
                    see https://verbump.de/ for what these numbers do

        Infrastructure:
            #589  CI: Upgrade Clang from 13 to 14

        Special thanks to:
            evpobr
            Kai Pastor
            Sam James

(wiz)