RFR: 8253148: Fix terminology in align_down comment

[Kim Barrett]

> On Sep 15, 2020, at 3:00 AM, Aleksey Shipilev <shade at openjdk.java.net> wrote:
> 
> On Tue, 15 Sep 2020 06:40:41 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:
> 
>> Please review this trivial terminology change in a comment.  This was supposed to be part of JDK-8247910, but I forgot
>> to push this comment change before integrating.
> 
> Marked as reviewed by shade (Reviewer).
> 
> -------------
> 
> PR: https://git.openjdk.java.net/jdk/pull/166

Thanks.