RFR: CODETOOLS-7903251: ProblemList test fails on M1 Mac

[Jonathan Gibbons]

Please review a test fix for a jtreg self-test.(There's also an update to a comment in a source file.)

This one is somewhat interesting.  Despite the name `System.getProperty("os.arch")` depends on the JDK being run, more than anything derived from `uname`.  In particular, for older JDKs on an M1 Mac, they report `os.arch` as the older `x86_64`, since older JDKs, up to JDK 11.0.15 inclusive, do not come as `aarch64` binaries.   But newer JDKs do report `os.arch` as `aarch64`.   

The fix for the test is to use the JDK being tested to update the problem-list template with the values that it will recognize when used as the test OS.  Tested with `JDKHOME` set to  JDK 11.0.15 and JDK 17.

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Commit messages:
 - CODETOOLS-7903251: ProblemList test fails on M1 Mac

Changes: https://git.openjdk.org/jtreg/pull/102/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=102&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903251
  Stats: 68 lines in 3 files changed: 57 ins; 7 del; 4 mod
  Patch: https://git.openjdk.org/jtreg/pull/102.diff
  Fetch: git fetch https://git.openjdk.org/jtreg pull/102/head:pull/102

PR: https://git.openjdk.org/jtreg/pull/102