[jdk8u] RFR: 8303408 : [AIX] Broken jdk8u build after JDK-8266391

[Paul Hohensee]

On Thu, 2 Mar 2023 10:18:18 GMT, Deepa Kumari <duke at openjdk.org> wrote:

> The AIX build fails after [JDK-8266391](https://bugs.openjdk.org/browse/JDK-8266391) was backported to jdk8. So, We added null returning SystemMetrics class an aix platform specific class that fixes the build error.
> 
> Reported Issue : [JDK-8303408](https://bugs.openjdk.org/browse/JDK-8303408)

Tagged the JBS issue.

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PR: https://git.openjdk.org/jdk8u/pull/33