RFR: 8246045: ZGC: Fix ZDirector::rule_high_usage() calculation

[Erik Österlund]

+1

/Erik

> On 28 May 2020, at 10:21, Per Liden <per.liden at oracle.com> wrote:
> 
> When ZDirector::rule_high_usage() calculates the amount of free space, it should take into account that "used" could be higher than "soft_max_capacity". Just like we do inZDirector::rule_allocation_rate().
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8246045
> Webrev: http://cr.openjdk.java.net/~pliden/8246045/webrev.0
> 
> /Per