[lworld] RFR: 8298659: [lworld] ValueObject isSubstutitable comparison of float/double should use raw bits

[Roger Riggs]

Update the substitutability implementation to match the new JLS for JEP 401.
Float and double values should be compared for equality using the raw bits.

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Commit messages:
 - 8298659: [lworld] ValueObject isSubstutitable comparison of float/double should use raw bits

Changes: https://git.openjdk.org/valhalla/pull/998/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=998&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8298659
  Stats: 54 lines in 3 files changed: 38 ins; 4 del; 12 mod
  Patch: https://git.openjdk.org/valhalla/pull/998.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/998/head:pull/998

PR: https://git.openjdk.org/valhalla/pull/998