RFR: JDK-8286256 : Update libxml2 to 2.9.14 [v2]

[Hima Bindu Meda]

> Updated libxml to version 2.9.14.As mentioned in UPDATING.txt, configured for windows , linux and Mac platforms and updated the files accordingly.
> 
> Updated libxslt to version 1.1.35. Generated the config.h files for windows , Mac and linux platforms and updated accordingly.
> 
> Verified the build on all the platforms and sanity testing looks fine.No regressions observed.

Hima Bindu Meda has updated the pull request incrementally with one additional commit since the last revision:

  Add UPDATING.txt for libxslt update

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/797/files
  - new: https://git.openjdk.java.net/jfx/pull/797/files/7af0e74b..b9091ece

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=797&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=797&range=00-01

  Stats: 36 lines in 1 file changed: 36 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/797.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/797/head:pull/797

PR: https://git.openjdk.java.net/jfx/pull/797