RFR: 8277946: NMT: Deprecate and remove VM.native_memory shutdown jcmd command option

[Aleksey Shipilev]

On Tue, 30 Nov 2021 15:17:10 GMT, Zhengyu Gu <zgu at openjdk.org> wrote:

> NMT shutdown functionality is a remnant of its first implementation, which could consume excessive amount of memory, therefore, it needed capability to shut it self down to ensure health of JVM. This is no longer a case for new implementation.
> 
> NMT shutdown can be requested via Jcmd. However, it is rare used.
> 
> We should deprecate for shutdown Jcmd command for removing NMT shutdown functionality.
> 
> Corresponding [CSR](https://bugs.openjdk.java.net/browse/JDK-8277947) has been approved.

Looks fine. I wonder: was `NMT_minimal` the state after "shutdown"? If so, should it be removed too? (in separate PR, probably)

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Marked as reviewed by shade (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/6618