libxml2: Update to version 2.14.6

libxml2: Update to version 2.14.6

- Update from version 2.14.4 to 2.14.6
- Update of rootfile
- 5 CVE fixes in version 2.14.5
- Changelog
    2.14.6
	Regressions
	    valid: Don't add ids when validating entity content
	    Fix initGenericErrorDefaultFunc(NULL) (Samuel Thibault)
	    valid: Undeprecate xmlAdd*Decl
	    globals: Include HTMLparser.h, fixing Windows build
	    io: Fix reading from pipes like stdin on Windows
	Security
	    regexp: Avoid integer overflow and OOB array access
	    tree: Guard against atype corruption
	Improvements
	    parser: Fix xmlSaturatedAddSizeT argument type
    2.14.5
	Regressions
	    valid: Don't add ids when validating entity content
	    io: Fix reading from pipes like stdin on Windows
	    parser: Fix handling of invalid char refs in recovery mode
	Security
	    regexp: Avoid integer overflow and OOB array access
	    tree: Guard against atype corruption
	    [CVE-2025-49794] [CVE-2025-49796] schematron: Fix xmlSchematronReportOutput
	    [CVE-2025-49795] schematron: Fix null pointer dereference leading to DoS
		(Michael Mann)
	    [CVE-2025-6170] Fix potential buffer overflows of interactive shell
		(Michael Mann)
	    [CVE-2025-6021] tree: Fix integer overflow in xmlBuildQName
	Bug fixes
	    save: Fix serialization of attribute defaults containing <
	Improvements
	    parser: Fix xmlSaturatedAddSizeT argument type
	Build systems and portability
	    meson: Add libxml2 part of include dir to pc file (Heiko Becker)
	    cmake: Fix installation directories in libxml2-config.cmake
	    io: Fix linkage of __xml*BufferCreateFilename functions

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