libxml2: Update to 2.9.12

Drop CVE patches which are fixed by the new upstream version.

Modify conflicting patches to apply to the new versions:
   libxml2/libxml-m4-use-pkgconfig.patch
   libxml2/0001-Make-ptest-run-the-python-tests-if-python-is-enabled.patch

Drop fix-python39, which is merged upstream.

Removed hunk for tstLastError.py from
   libxml2/0001-Make-ptest-run-the-python-tests-if-python-is-enabled.patch
since it has been fixed upstream by:

   8c3e52e: Updated python/tests/tstLastError.py

   libxml2.registerErrorHandler(None,None):
   None is not acceptable as first argument
   failUnlessEqual replaced by assertEqual

The checksums for the licence file changed because a typo was fixed
across the files. The licence remains the same.
The obsolete MD5 checksums for the tar files have been dropped in
favor of SHA256.

The new release also adds fuzz tests, which are removed from the
makefile to allow the ptests to run. Fuzz testing is done upstream
and there is no need to run them as part of ptests which are
intended for functionality testing.

Signed-off-by: Tony Tascioglu <tony.tascioglu@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>