[jdk25u] RFR: 8364198: NMT should have a better corruption message

[Rui Li]

A clean backport of https://bugs.openjdk.org/browse/JDK-8364198.

This patch improves the error message, quite straight forward as the error message itself - NMT detected a bug somewhere else, but not in itself. Error message change. Low risks.

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Commit messages:
 - Backport 2202156acc78d7d9ec128f8df5c09fcdff83697c

Changes: https://git.openjdk.org/jdk25u/pull/179/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk25u&pr=179&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8364198
  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk25u/pull/179.diff
  Fetch: git fetch https://git.openjdk.org/jdk25u.git pull/179/head:pull/179

PR: https://git.openjdk.org/jdk25u/pull/179