RFR: 8263551: Provide shared lock-free FIFO queue implementation [v4]

[Man Cao]

On Wed, 31 Mar 2021 10:35:59 GMT, Ivan Walulya <iwalulya at openjdk.org> wrote:

>> Man Cao has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Revise comments and move trailing padding.
>
> Marked as reviewed by iwalulya (Committer).

Thank you for the reviews!

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PR: https://git.openjdk.java.net/jdk/pull/2986