RFR: 7902820: Asmtools incorrectly uses stdout for output error messages

[Leonid Kuskov]

[CODETOOLS-7902820](https://bugs.openjdk.org/browse/CODETOOLS-7902820): Asmtools incorrectly uses stdout for output error messages

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Commit messages:
 - CODETOOLS-7902820: Asmtools incorrectly uses stdout for output error messages

Changes: https://git.openjdk.org/asmtools/pull/81/files
  Webrev: https://webrevs.openjdk.org/?repo=asmtools&pr=81&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7902820
  Stats: 216 lines in 6 files changed: 199 ins; 2 del; 15 mod
  Patch: https://git.openjdk.org/asmtools/pull/81.diff
  Fetch: git fetch https://git.openjdk.org/asmtools.git pull/81/head:pull/81

PR: https://git.openjdk.org/asmtools/pull/81