RFR: JDK-8325496: Make TrimNativeHeapInterval a product switch [v3]

[Thomas Stuefe]

> [JDK-8293114](https://bugs.openjdk.org/browse/JDK-8293114) introduced automatic C-heap trimming, for now supported only by the glibc. It is controlled by the command line switch `TrimNativeHeapInterval`. The feature has proven very valuable to customers, and all issues have been ironed out. So, I'd like to make this switch a non-experimental product switch.

Thomas Stuefe 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 five additional commits since the last revision:

 - man change
 - Merge branch 'master' into JDK-8325496-Make-TrimNativeHeapInterval-a-product-switch
 - Feedback David
 - Manpage
 - JDK-8325496-Make-TrimNativeHeapInterval-a-product-switch

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17799/files
  - new: https://git.openjdk.org/jdk/pull/17799/files/15e4527c..093536d2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17799&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17799&range=01-02

  Stats: 22830 lines in 616 files changed: 8476 ins; 10063 del; 4291 mod
  Patch: https://git.openjdk.org/jdk/pull/17799.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17799/head:pull/17799

PR: https://git.openjdk.org/jdk/pull/17799