Detect crashes in CompilationTestHelper independently of the default locale

[kumarprabhashanand]

Fixes #6178

CompilationTestHelper detected compiler crashes by searching for javac's English crash banner, which javac localizes. Under locales such as de_DE, ja_JP, and zh_CN, crashes could go unnoticed.

Use JavacTaskImpl.doCall() and fail on Result.ABNORMAL instead. Preserve the existing OK/ERROR behavior of expectResult() for all other results.

Add regression tests for crash detection across five locales and for SYSERR still being reported as ERROR. The locale test also verifies that Japanese output does not contain the English crash banner.

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