RFR(XS) 8184991: NMT detail diff should take memory type into account

[Zhengyu Gu]

After JDK-8139673, there can be multiple malloc site records for a 
allocation path, but with different memory types.

When diffing the malloc sites, the comparison should be made to the 
sites, not only with the same allocation path, but also with the same 
memory type.

Bug: https://bugs.openjdk.java.net/browse/JDK-8184991
Webrev: http://cr.openjdk.java.net/~zgu/8184991/webrev.00/index.html


Test:

runtime/NMT tests with release and fastdebug builds.

Thanks,

-Zhengyu