expat: Update to version 2.4.6 - Security/CVE fixes

expat: Update to version 2.4.6 - Security/CVE fixes

- Update from 2.4.4 to 2.4.6
- Update of rootfile
- Changelog
   Release 2.4.6 Sun February 20 2022
      Bug fixes:
            #566  Fix a regression introduced by the fix for CVE-2022-25313
                    in release 2.4.5 that affects applications that (1)
                    call function XML_SetElementDeclHandler and (2) are
                    parsing XML that contains nested element declarations
                    (e.g. "<!ELEMENT junk ((bar|foo|xyz+), zebra*)>").
   Release 2.4.5 Fri February 18 2022
      Security fixes:
            #562  CVE-2022-25235 -- Passing malformed 2- and 3-byte UTF-8
                    sequences (e.g. from start tag names) to the XML
                    processing application on top of Expat can cause
                    arbitrary damage (e.g. code execution) depending
                    on how invalid UTF-8 is handled inside the XML
                    processor; validation was not their job but Expat's.
                    Exploits with code execution are known to exist.
            #561  CVE-2022-25236 -- Passing (one or more) namespace separator
                    characters in "xmlns[:prefix]" attribute values
                    made Expat send malformed tag names to the XML
                    processor on top of Expat which can cause
                    arbitrary damage (e.g. code execution) depending
                    on such unexpectable cases are handled inside the XML
                    processor; validation was not their job but Expat's.
                    Exploits with code execution are known to exist.
            #558  CVE-2022-25313 -- Fix stack exhaustion in doctype parsing
                    that could be triggered by e.g. a 2 megabytes
                    file with a large number of opening braces.
                    Expected impact is denial of service or potentially
                    arbitrary code execution.
            #560  CVE-2022-25314 -- Fix integer overflow in function copyString;
                    only affects the encoding name parameter at parser creation
                    time which is often hardcoded (rather than user input),
                    takes a value in the gigabytes to trigger, and a 64-bit
                    machine.  Expected impact is denial of service.
            #559  CVE-2022-25315 -- Fix integer overflow in function storeRawNames;
                    needs input in the gigabytes and a 64-bit machine.
                    Expected impact is denial of service or potentially
                    arbitrary code execution.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Reviewed-by: Michael Tremer <michael.tremer@ipfire.org>