RFR: 8283328: Update libxml2 to 2.9.13 [v2]

[Hima Bindu Meda]

On Fri, 1 Apr 2022 08:19:28 GMT, Hima Bindu Meda <hmeda at openjdk.org> wrote:

>> We currently use libxml2 version 2.9.12. It should be updated to latest stable release, which is version 2.9.13.
>> The steps to update libxml are documented in UPDATING.txt.
>> There is compilation issue with the release 2.9.13, as mentioned here: https://gitlab.gnome.org/GNOME/libxml2/-/issues/349.
>> Updated the code with the changes as per the fix mentioned in above link.
>> 
>> Compiled and verified on Windows, Mac and Linux platforms.
>> Sanity testing looks fine.
>
> Hima Bindu Meda has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add README.md and update libxml2.md

> 7. I see that the following files were deleted as part of this PR. Was this intentional?
> 
> ```
> D       modules/javafx.web/src/main/native/Source/ThirdParty/libxml/src/AUTHORS
> D       modules/javafx.web/src/main/native/Source/ThirdParty/libxml/src/ChangeLog
> D       modules/javafx.web/src/main/native/Source/ThirdParty/libxml/src/README
> ```

-- The above files have been deleted in the release v2.9.13.
Added README.md which contains information regarding Authors,License and libxml project

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PR: https://git.openjdk.java.net/jfx/pull/764