[Rev 03] RFR: 8246348: Crash in libpango on Ubuntu 20.04 with some unicode chars

[Johan Vos]

> This addresses https://bugs.openjdk.java.net/browse/JDK-8246348

Johan Vos has updated the pull request incrementally with one additional commit since the last revision:

  Add test for testing Pango behavior with Character(0) and surrogate pairs

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/249/files
  - new: https://git.openjdk.java.net/jfx/pull/249/files/0d6e9093..8c6e73a0

Webrevs:
 - full: https://webrevs.openjdk.java.net/jfx/249/webrev.03
 - incr: https://webrevs.openjdk.java.net/jfx/249/webrev.02-03

  Stats: 147 lines in 1 file changed: 147 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/249.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/249/head:pull/249

PR: https://git.openjdk.java.net/jfx/pull/249