RFR(s): 8250627: Use -XX:+/-UseContainerSupport for enabling/disabling Java container metrics

[Severin Gehwolf]

Hi,

Please review this patch which makes the Java container metrics adhere
to -XX:+/-UseContainerSupport so they can be disabled if heuristics
turn out to be wrong. The approach taken is to use JNI and call into
the JVM in order to determine the setting of UseContainerSupport before
Metrics are being instantiated.

The intention is for this patch to be backported to older JDKs so as to
provide a means to disable container metrics should things go wrong
with backports of the likes of JDK-8226575.

Bug: https://bugs.openjdk.java.net/browse/JDK-8250627
webrev: https://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8250627/01/webrev/

Testing: New container test. Existing container tests. jdk/submit.
         tier1 on Linux x86_64.

Thoughts?

Thanks,
Severin