[Issue 8227] syncprov should use more threads

https://bugs.openldap.org/show_bug.cgi?id=8227

--- Comment #4 from Ondřej Kuzník ondra@mistotebe.net --- Maybe you meant something else because I'm not seeing this, syncprov_matchops->syncprov_qresp already schedules a separate syncprov_qtask for each active persist session that has anything to send out. Those sessions each have a separate response queue, sharing a reference to the resinfo provided.

And those tasks then run independent of each other sending messages (since ITS#5985 just one message at a time), reclaiming syncres and since ITS#8039 possibly resinfo as they make progress. Also verified all of this at runtime.