[jdk21u-dev] RFR: 8344646: The libjsig deprecation warning should go to stderr not stdout

[Goetz Lindenmaier]

I backport this for parity with 21.0.7-oracle

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Commit messages:
 - Backport efeacfee015d1105dcd75e489d367a7716441fa8

Changes: https://git.openjdk.org/jdk21u-dev/pull/1267/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1267&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344646
  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1267.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1267/head:pull/1267

PR: https://git.openjdk.org/jdk21u-dev/pull/1267