8204163: Also detect concurrent GCs in MetaspaceBaseGC.java

[Stefan Karlsson]

Hi all,

Please review this patch to allow MetaspaceBaseGC.java to detect 
concurrent GC cycles that are started because of Metaspace allocations.

http://cr.openjdk.java.net/~stefank/8204163/webrev.01/
https://bugs.openjdk.java.net/browse/JDK-8204163

The old code only checked for Full GCs, and now we also match concurrent 
cycles.

This has been tested with the vmTestbase/metaspace/gc tests with G1, 
CMS, and Z.

Thanks,
StefanK