RFR(XXS): 8141056: Erroneous assignment in HeapRegionSet.cpp

[David Lindholm]

Hi,

Please review this tiny patch that changes an assignment into an equals 
check.

Bug: https://bugs.openjdk.java.net/browse/JDK-8141056
Webrev: http://cr.openjdk.java.net/~david/JDK-8141056/webrev.00/

Testing: Passed JPRT and vm.gc testlist.


Thanks,
David