Fix AVX2 detection on other platforms

[naveentatikonda]

Description

Fix NPE while detecting AVX2 on other platforms(other than Linux, Mac and Windows)

java.lang.NullPointerException: Cannot invoke "java.lang.Boolean.booleanValue()" because "org.opensearch.knn.jni.Platfor
mUtils.isAVX2Supported" is null
        at org.opensearch.knn.jni.PlatformUtils.isAVX2SupportedBySystem(PlatformUtils.java:98)
        at org.opensearch.knn.plugin.KNNPlugin.lambda$static$0(KNNPlugin.java:183)
        at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1423)
        at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:387)
        at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1312)
        at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1843)
        at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1808)
        at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:188)

Related Issues

Resolves #2788

Check List

• New functionality includes testing.
• New functionality has been documented.
• API changes companion pull request created.
• Commits are signed per the DCO using --signoff.
• Public documentation issue/PR created.

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[Vikasht34]

Looks good

[navneet1v]

somehow I see just the Changelog file present in the file diff. Something is wrong here.

[navneet1v]

how does this solves the NPE? is it like on windows even when user has disabled the AVX2 we were still checking isIntel || isWindows() ?

[naveentatikonda]

This is just to terminate and return early. This is the detection logic which will check if user has enabled or disabled AVX2 based on OS.

NPE is happening when it is ran on some other platform like FreeBSD other than linux, windows and mac because the default value of isAVX2Supported is null. So, we are fixing it here by returning false if it is still null