[TESTBUG] runtime/containers/docker/TestCPUAwareness.java failed in docker not supporting --cpus

[Ao Qi]

Hi,

--cpus is available in Docker 1.13 and higher [1], so
runtime/containers/docker/TestCPUAwareness.java failed in docker which
does not support --cpus.

Webrev: http://cr.openjdk.java.net/~aoqi/docker/webrev.00/

This patch skips the test if --cpus is not supported. I tested
runtime/containers/docker/TestCPUAwareness.java on a Fedora 25 (Docker
version 1.12.6, build ae7d637/1.12.6, not supporting --cpus) and
Ubuntu 16.04 (Docker version 17.03.2-ce, build f5ec1e2, supporting
--cpus)

I am not sure if this is a testbug, so I did not file it on JBS. In
fact, I am not quite sure what kind of issue can be filed on JBS. Is
there any guidance document?

Cheers,
Ao Qi

[1] https://docs.docker.com/config/containers/resource_constraints/#cpu