[jdk11u-dev] RFR: 8304074: [JMX] Add an approximation of total bytes allocated on the Java heap by the JVM

[Paul Hohensee]

I'd like to backport the definition and implementation of com.sun.management.ThreadMXBean.getTotalThreadAllocatedBytes to 11u. The backport CSR is [JDK-8320375](https://bugs.openjdk.org/browse/JDK-8320375). A follow-up bugfix backport of [JDK-8313081](https://bugs.openjdk.org/browse/JDK-8313081) will be done following this backport. The combined backports have been in production at Amazon for two months with no issues. The backport uses the reserved6 slot in jmm.h in order to preserve binary compatibility with 11u. Per current policy, there is no update to JMM_VERSION in jmm.h and the new method is marked

@since 11.0.22

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Commit messages:
 - 8304074: Update getTotalThreadAllocatedBytes @since to 11.0.22
 - Merge branch 'master' into backport-8304074
 - Merge branch 'master' into backport-8304074
 - Merge branch 'master' into backport-8304074
 - Merge branch 'master' into backport-8304074
 - Backport 3eced01f9efe2567a07b63343f8559683a2d0517

Changes: https://git.openjdk.org/jdk11u-dev/pull/2286/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2286&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304074
  Stats: 299 lines in 12 files changed: 219 ins; 45 del; 35 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2286.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2286/head:pull/2286

PR: https://git.openjdk.org/jdk11u-dev/pull/2286