RFR: 8253928: G1: Remove G1ConcurrentMarkThread::set_in_progress declaration

[Aleksey Shipilev]

On Fri, 2 Oct 2020 11:01:48 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> There is no definition of G1ConcurrentMarkThread::set_in_progress since JDK-8240556 any more, so also remove the
>> declaration in this trivial change.
>> Testing: local compilation
>
> Marked as reviewed by shade (Reviewer).

...and yes, it is trivial.

-------------

PR: https://git.openjdk.java.net/jdk/pull/480