RFR: 8304074: [JMX] Add an approximation of total bytes allocated on the Java heap by the JVM [v14]

[Paul Hohensee]

> Please review this addition to com.sun.management.ThreadMXBean that returns the total number of bytes allocated on the Java heap since JVM launch by both terminated and live threads.
> 
> Because this PR adds a new interface method, I've updated the JMM_VERSION to 4, but would be happy to update it to 3_1 instead.

Paul Hohensee has updated the pull request incrementally with three additional commits since the last revision:

 - 8304074: set _atomic_add_long_entry = ShouldNotCallThisStub()
 - 8304074: update jmm_GetTotalAllocatedBytes comment
 - 8304074: Use __atomic_add_fetch rather than TBD assembler stub

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/13814/files
  - new: https://git.openjdk.org/jdk/pull/13814/files/ab830a80..5515fc59

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13814&range=13
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13814&range=12-13

  Stats: 42 lines in 3 files changed: 16 ins; 15 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/13814.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13814/head:pull/13814

PR: https://git.openjdk.org/jdk/pull/13814