RFR: 8279005: sun/tools/jstat tests do not check for test case exit codes after JDK-8245129

[Paul Hohensee]

jstat test-only fix.

1. Ensure that jstat tests that run more than one sub-test per test file check the result of each sub-test before continuing.
2. Allow '-' as a valid jstat -gcutil heap space percent occupancy field value, see lineCounts[1-4].awk. Occupancy is computed as ((capacity - used) / capacity), see src/jdk.jcmd/share/classes/sun/tools/jstat/resources/jstat_options, search for "gcutil". G1, ZGC, and Shenandoah may return zero capacity for any or all of survivor spaces, eden, old gen, metaspace, and compressed class space, leading to an occupancy result represented '-'.

Modified tests pass.

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Commit messages:
 - 8279005: sun/tools/jstat tests do not check for test case exit codes after JDK-8245129

Changes: https://git.openjdk.org/jdk/pull/25951/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25951&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8279005
  Stats: 76 lines in 16 files changed: 60 ins; 0 del; 16 mod
  Patch: https://git.openjdk.org/jdk/pull/25951.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25951/head:pull/25951

PR: https://git.openjdk.org/jdk/pull/25951