RFR (XS) 8058818: Allocation of more then 1G of memory using Unsafe.allocateMemory is still causi,ng a fatal error on 32bit platforms

[Coleen Phillimore]

Summary: The assert was firing for NMT_Off and minimal too even though 
the size isn't used.

open webrev at http://cr.openjdk.java.net/~coleenp/8058818/
bug link https://bugs.openjdk.java.net/browse/JDK-8058818

Tested with the NMT tests.

thanks,
Coleen