RFR(XXS) 8190357: NMT: Include metadata information in NMT final report when PrintNMTStatistics is on

[Zhengyu Gu]

This patch adds metadata reporting in NMT final report.

What complicates the matter, is that, reporting per-class loader 
metadata requires a safepoint, so that it can safely walk class loaders. 
So, we only report it when JVM is about to exit in good state.


Bug: https://bugs.openjdk.java.net/browse/JDK-8190357
Webrev: http://cr.openjdk.java.net/~zgu/8190357/webrev.00/


Thanks,

-Zhengyu