RFR: 8266184: a few compiler/debug tests don't check exit code

[Igor Ignatyev]

Hi all,

could you please review this small fix for `compiler/debug` tests?
from JBS:
> `compiler/debug/TestGenerateStressSeed.java`, `TestStressCM.java`, and `TestStressIGVNAndCCP.java` don't check the exit code of spawned JVMs, as a result, they might miss misconfiguration and/or defects. in fact, `TestStressIGVNAndCCP.java` uses a wrong flag name (`TraceIterativeIGVN` instead of `TraceIterativeGVN`) and this was unnoticed b/c we didn't check the exit code.

the patch adds calls to `OutputAnalyzer::shouldHaveExitValue` and fixes `TestStressIGVNAndCCP.java` to use the right flag.

testing:
- [x] `test/hotspot/jtreg/compiler/debug` on `linux-x64-debug`

Thanks,
-- Igor

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Commit messages:
 - copyright year
 - 8266184

Changes: https://git.openjdk.java.net/jdk/pull/3748/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3748&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8266184
  Stats: 7 lines in 3 files changed: 3 ins; 1 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3748.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3748/head:pull/3748

PR: https://git.openjdk.java.net/jdk/pull/3748