For https://gitlab.winehq.org/wine/wine/-/merge_requests/7226
This MR introduces a new wineserver "sync" entity, to be used by objects to implement the signal/wait operations. Later, the server sync implementations will be reduced as much as possible to event/mutex/semaphore/queue[^1]. I think it will then make the integration of ntsync cleaner, with inproc syncs being a separate flavor from the traditional server-side syncs.
Unlike how the fd struct have been implemented, I chose not to derive these syncs from the object base, because it seemed inconvenient to have to declare all the unused ops. Still they are refcounted, to allow us to share a sync between multiple objects, which will later benefit the console objects use cases, maybe others.
This makes me thing that the fd struct could also benefit from being lightweight entities as well, as it doesn't seem they really use most of the object vtable ops, and arguably we could have a common "light" refcounted/dumpable base for all fds, syncs and objects, but I didn't want to jump into that rabbit hole and it could be implemented later.
[^1]: And server-only async/completion waits, which maybe can be changed to use events too, but I'm not familiar enough.