RFR: 8301009: Update libxml2 to 2.10.3

[Hima Bindu Meda]

Updated Libxml2 to v2.10.3. verfied build and sanity testing on windows, mac and Linux platforms.
No issue observed.

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Commit messages:
 - White space corrections
 - white space correction
 - update libxml2.md
 - Remove unwanted files
 - configure libxml to v2.10.3 on linux
 - configure libxml v2.10.3 on windows
 - Update libxml to v2.10.3

Changes: https://git.openjdk.org/jfx/pull/1058/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1058&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/jfx/pull/1058.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/1058/head:pull/1058

PR: https://git.openjdk.org/jfx/pull/1058