RFR(S) 8193184: NMT: Report array class count in NMT summary

[Zhengyu Gu]

Please review this patch that adds array class count to NMT report, so 
the class count can closely match the output from GC.class_stats.

For example:
Summary:
-                     Class (reserved=1069781KB, committed=1069269KB)
                             (classes #3362)
                             (  instance classes# 3105, array classes#257)

Summary diff:
-                     Class (reserved=1071843KB +2061KB, 
committed=1070051KB +781KB)
                             (classes #3405 +43)
                             (  instance classes# 3143 +38, array 
classes#262 +5)

Bug: https://bugs.openjdk.java.net/browse/JDK-8193184
Webrev: http://cr.openjdk.java.net/~zgu/8193184/webrev.00/

Test:
   hotspot_tier1_runtime on Linux 64 (fastdebug and release)

Thanks,

-Zhengyu