[jfx11u] Integrated: 8301009: Update libxml2 to 2.10.3

[Johan Vos]

Clean backport for 
8301009: Update libxml2 to 2.10.3
Reviewed-by: kcr, sykora

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Commit messages:
 - 8301009: Update libxml2 to 2.10.3

Changes: https://git.openjdk.org/jfx11u/pull/140/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx11u&pr=140&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8301009
  Stats: 6301 lines in 80 files changed: 1128 ins; 4562 del; 611 mod
  Patch: https://git.openjdk.org/jfx11u/pull/140.diff
  Fetch: git fetch https://git.openjdk.org/jfx11u.git pull/140/head:pull/140

PR: https://git.openjdk.org/jfx11u/pull/140