RFR: 8277930: Add unsafe allocation event to jfr [v4]

[xpbob]

On Tue, 30 Nov 2021 07:27:27 GMT, xpbob <duke at openjdk.java.net> wrote:

>> Unsafe is used in many Java frameworks.
>> When the framework has a unsafe memory leak , there is no way to know what code is causing it.
>> Add unsafe allocation event to jfr.
>> Records the size and stack allocated.
>> This event is off by default
>
> xpbob has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove whitespace

Thanks
I added 3 events
|event|stack|addr|size|
|-|-|-|-|
|Allocation|true|alloc|true|
|Reallocate|true|before realloc,after realloc|true|
|Free|true|free addr|false|

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PR: https://git.openjdk.java.net/jdk/pull/6591