RFR: 7903524: Permit more segments in jtreg tags

[Christian Stein]

Please review this change to permit more segments in jtreg tags, for example: `jtreg-7.3.1+1`.

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Commit messages:
 - Permit more segments in jtreg tags

Changes: https://git.openjdk.org/jtreg/pull/169/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=169&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903524
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jtreg/pull/169.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/169/head:pull/169

PR: https://git.openjdk.org/jtreg/pull/169