RFR: 8352162: Update libxml2 to 2.13.8 [v6]

[Kevin Rushforth]

On Mon, 21 Apr 2025 17:28:12 GMT, Jay Bhaskar <jbhaskar at openjdk.org> wrote:

>> The upgrade is required to address several known issues from the previous version to improve stability and performance.
>
> Jay Bhaskar has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove unused files

> > I see several files were added in this update that aren't part of the 2.12.x --> 2.13.x update (e.g., `xmlschemas.c`). Can you check whether these are actually needed? I suspect that most aren't.
> 
> Here is the complete list for you to check:
> 
> ```
> ...
> libxml/src/include/private/Makefile.am
> libxml/src/include/private/regexp.h
> libxml/src/include/private/xinclude.h
> libxml/src/include/private/xzlib.h
> ```

Turns out that least one of the .h files in `libxml/src/include/private/` -- `regexp.h` -- is needed, so at least that one (and maybe the others) should not be removed.

-------------

PR Comment: https://git.openjdk.org/jfx/pull/1785#issuecomment-2819746296