RFR: 8301627: System.exit and Runtime.exit debug logging [v3]

[Roger Riggs]

> It can be difficult to find the cause of calls to `java.lang.System.exit(status)` and `Runtime.exit(status)` because the Java runtime exits.
> The status value and stack trace are logged using the System Logger named `java.lang.Runtime` with message level `System.Logger.Level.DEBUG`.

Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:

  Add an @implNote to Runtime.exit to describe the java.lang.Runtime logging.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12517/files
  - new: https://git.openjdk.org/jdk/pull/12517/files/76c4d61f..a8eca9e5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12517&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12517&range=01-02

  Stats: 32 lines in 2 files changed: 18 ins; 12 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/12517.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12517/head:pull/12517

PR: https://git.openjdk.org/jdk/pull/12517