[lworld] RFR: 8372955: [lworld] The alternate substitutability method doesn't increment the offset when iterating over segments

[Frederic Parain]

Fix missing offset increment in the alternate substitutability test method.

The unit tests forces the use of the alternate substitutability test method because the legacy method has another issue of its own with some of the tests (see JDK-8372729)

Fred

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Commit messages:
 - Remove trailing whitespaces
 - Fix formating
 - Fix offset increment in alt substitutability method

Changes: https://git.openjdk.org/valhalla/pull/1769/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1769&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8372955
  Stats: 206 lines in 2 files changed: 206 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/valhalla/pull/1769.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1769/head:pull/1769

PR: https://git.openjdk.org/valhalla/pull/1769