[jdk17u] RFR: 8268893: jcmd to trim the glibc heap

[Thomas Stuefe]

Hi,

may I please have reviews for this clean backport of 8268893: "jcmd to trim the glibc heap"? 

The command turned out to be very useful to us when analyzing suspected memory leaks. It would be nice to have this in JDK 17.

The associated downport-CSR had been provisionally approved.

Thank you, Thomas

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Commit messages:
 - Backport 6096dd9765eaf280890f65c0ff1ab64864b9316a

Changes: https://git.openjdk.java.net/jdk17u/pull/70/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=70&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268893
  Stats: 248 lines in 6 files changed: 222 ins; 9 del; 17 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/70.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/70/head:pull/70

PR: https://git.openjdk.java.net/jdk17u/pull/70