Integrated: 8264123: add ThreadsList.is_valid() support

[Daniel D.Daugherty]

On Mon, 29 Mar 2021 21:48:23 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

> ThreadsLists need an is_valid() function and checks in various
> places to help catch bugs where a ThreadsList is dangling.
> 
> Other minor changes:
> - change raw `_threads_hazard_ptr` access to used `get_threads_hazard_ptr()`.
> - `get_threads_hazard_ptr()` should be `const`.
> - fix a couple of old typos.
> 
> Update: forgot to mention that this fix was tested with Mach5 Tier[1-8].

This pull request has now been integrated.

Changeset: 9b2232bc
Author:    Daniel D. Daugherty <dcubed at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/9b2232bc
Stats:     60 lines in 4 files changed: 48 ins; 0 del; 12 mod

8264123: add ThreadsList.is_valid() support

Reviewed-by: dholmes, eosterlund, rehn

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

PR: https://git.openjdk.java.net/jdk/pull/3255