[jdk21] RFR: 8310861: Improve location reporting for javac serial lint warnings

[Joe Darcy]

Backport to JDK 21.

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Commit messages:
 - Backport 289f218a32558bbbf7e6c589b4618757bd6d043f

Changes: https://git.openjdk.org/jdk21/pull/63/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21&pr=63&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310861
  Stats: 52 lines in 9 files changed: 24 ins; 0 del; 28 mod
  Patch: https://git.openjdk.org/jdk21/pull/63.diff
  Fetch: git fetch https://git.openjdk.org/jdk21.git pull/63/head:pull/63

PR: https://git.openjdk.org/jdk21/pull/63