RFR: 8325517: Shenandoah: Reduce unnecessary includes from shenandoahControlThread.cpp

[Y. Srinivas Ramakrishna]

On Thu, 8 Feb 2024 18:32:46 GMT, William Kemper <wkemper at openjdk.org> wrote:

> The control thread used to run much more of the cycle directly. This code was all factored out into different classes, but many of the vestigial headers remained. Removing these improves compilation times and makes maintenance easier.

Looks good modulo Aleksey's suggestion on checking use of header file's content in compilation unit rather than relying on serendipitous (and fragile) transitive dependencies.

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

Marked as reviewed by ysr (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/17778#pullrequestreview-1871265523