RFR(XS): JDK-8073883 - serviceability/dcmd/gc/RunGCTest.java should not run with -XX:+ExplicitGCInvokesConcurrent

[Jesper Wilhelmsson]

Hi,

Please review this minor fix to add -XX:-ExplicitGCInvokesConcurrent to this 
test. The test expects messages from a full GC and will not work if 
ExplicitGCInvokesConcurrent is enabled.

This is a critical nightly issue (since it causes the test to fail often enough).

Bug: https://bugs.openjdk.java.net/browse/JDK-8073883
Webrev: http://cr.openjdk.java.net/~jwilhelm/8073883/webrev.00/

Thanks,
/Jesper