[8u] RFR: 8247469: getSystemCpuLoad() returns -1 on linux when some offline cpus are present and cpusets.effective_cpus is not available

[Severin Gehwolf]

Hi,

This is a prerequisite backport for JDK-8265836, which I'd like to
bring to OpenJDK 8u as the bug is present there too[2]. Note that the
OperatingSystemMXBean has been made container aware with JDK-8226575[1]
in 8u272 and better.

The OpenJDK 11u patch doesn't apply cleanly due to restructuring of the
code in later JDKs. The gist of the patch is still the same. One
addition of note is the mapfile-vers change for the new native method.

Bug: https://bugs.openjdk.java.net/browse/JDK-8247469
webrev: https://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8247469/jdk8/02/webrev/

Testing: Builds on Linux x86_64, Solaris Sparc, AIX.
         Manually via the reproducer for JDK-8265836. Tier 1 on Linux x86_64

Thoughts?

Thanks,
Severin

[1] https://bugs.openjdk.java.net/browse/JDK-8226575
[2] https://bugs.openjdk.java.net/browse/JDK-8269874?focusedCommentId=14432127&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-14432127