RFR: 8370207: Test sun/misc/SunMiscSignalTest.java crashes after JDK-8369631 [v2]

[David Holmes]

> I missed that the `UserHandler` can still be used even if `-Xrs` is specified, so we have to check for `!ReduceSignalUsage` as per Kim's initial suggestion in JDK-8369631.
> 
> Testing
> - tiers 1-4
> 
> Thanks

David Holmes has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Un-ProblemList the test
 - Merge branch 'master' into 8370207-sem_notify-crash
 - 8370207: Test sun/misc/SunMiscSignalTest.java crashes after JDK-8369631

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/27888/files
  - new: https://git.openjdk.org/jdk/pull/27888/files/ed3227a7..9a69dd1e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27888&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27888&range=00-01

  Stats: 14 lines in 2 files changed: 6 ins; 2 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/27888.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27888/head:pull/27888

PR: https://git.openjdk.org/jdk/pull/27888