RFR 8250984: Memory Docker tests fail on some Linux kernels w/o swap limit capabilities

[Harold Seigel]

Hi,

Please review this fix to enable docker tests TestMemoryAwareness.java 
and TestDockerMemoryMetrics.java to run on Linux kernels configured 
without swap limit capabilities.

Open Webrev: 
http://cr.openjdk.java.net/~hseigel/bug_8250984.dkr/webrev/index.html

JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8250984

The modified tests were run on Linux kernels with and without swap limit 
capabilities.

Thanks, Harold