RFR: 8178352: BitMap::get_next_zero_offset may give wrong result on Mac

[Kim Barrett]

> On Apr 10, 2017, at 12:18 PM, Kim Barrett <kim.barrett at oracle.com> wrote:
>> You did a couple of stylistic changes that now make the code inconsistent:
>> 
>> […]
>> I think these changes should be kept out of this patch.
> 
> Post-decrement in for loops still makes me twitch, even though it doesn’t matter
> in this code base.  But okay.

Updated webrev:
http://cr.openjdk.java.net/~kbarrett/8178352/hotspot.01/