RFR: 8352162: Update libxml2 to 2.13.8 [v7]

[Jay Bhaskar]

> 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 non required files as by review

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1785/files
  - new: https://git.openjdk.org/jfx/pull/1785/files/5c4b05d0..95275e7a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1785&range=06
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1785&range=05-06

  Stats: 99839 lines in 61 files changed: 1 ins; 99836 del; 2 mod
  Patch: https://git.openjdk.org/jfx/pull/1785.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1785/head:pull/1785

PR: https://git.openjdk.org/jfx/pull/1785