RFR 8204128: NMT might report incorrect numbers for Compiler area

[Zhengyu Gu]

I could not reproduce the problem stated in CR.

The theory is that, when releasing a 2GB+ arena, 
Arena::set_size_in_bytes() passes a negative long integer to NMT, when 
it goes through long -> int -> long conversion, at the end, it becomes a 
positive number.

This problem is illustrated in new test. Without the fix, after 
releasing a 2GB+ arena, NMT shows the arena size doubled, instead of 
going down.

I am not completely sure this fixes the problem reported, but it is 
worth to cleanup inconsistent types in NMT API.


Bug: http://cr.openjdk.java.net/~zgu/JDK-8204128/webrev.00/index.html
Webrev: http://cr.openjdk.java.net/~zgu/JDK-8204128/webrev.00/index.html

Test:
   hotspot_nmt + new test (fastdebug and release)
   on Linux x86_64

Thanks,

-Zhengyu