Replace the test case for the child writing to stderr and then exit 1. `cat` on AIX writes the error message to stdout. Use JavaChild instead of `cat` to have the same sequence of output, input, and exit status.
------------- Commit messages: - 8371421: [AIX] new test ProcessCloseTest fails Changes: https://git.openjdk.org/jdk/pull/28185/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28185&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8371421 Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod Patch: https://git.openjdk.org/jdk/pull/28185.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/28185/head:pull/28185 PR: https://git.openjdk.org/jdk/pull/28185
