RFR: 7903792: ReportOnlyTest may fail in "headless" environments

Mon Aug 19 23:37:06 UTC 2024

Please review a test-only fix to the problems observed running `ReportOnlyTest.gmk`, as seen in some GitHub actions for other PRs. 

The general problem that is addressed is inconsistent determination of a "headless" environment, as determined by `Basic.java` and as given by an env variable when running the tests. 

More details are given in the test itself.

-------------

Commit messages:
 - CODETOOLS-7903792: ReportOnlyTest may fail in "headless" environments

Changes: https://git.openjdk.org/jtreg/pull/223/files
  Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=223&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903792
  Stats: 26 lines in 2 files changed: 16 ins; 8 del; 2 mod
  Patch: https://git.openjdk.org/jtreg/pull/223.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/223/head:pull/223

PR: https://git.openjdk.org/jtreg/pull/223