RFR: 7904015: --verify-exclude fails to abort the test run when discovering failures

[Ludvig Janiuk]

Exit after discovering errors in exclude files

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Commit messages:
 - Exit after discovering errors in exclude files

Changes: https://git.openjdk.org/jtreg/pull/265/files
  Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=265&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7904015
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jtreg/pull/265.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/265/head:pull/265

PR: https://git.openjdk.org/jtreg/pull/265