RFR: GC.heap_info DCmd expects metaspace info

[Zhengyu Gu]

Hi,

Please review this trivial change that also output metaspace 
information. It is expected by GC.heap_info DCmd.

Webrev: http://cr.openjdk.java.net/~zgu/shenandoah/sh-heap-info/webrev.00/

Test:
   tier1_gc_shenandoah

Thanks,

-Zhengyu