context: report Task instance count

Report the number of Task objects that currently exist as well as the number
on the global work queue.

	THREADS (work queue 298 of 2385 tasks, 16 workers):

This helps spot leaks, since Task objects that are blocked on other Task
post-exec queues are otherwise invisible.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

src/bees-context.cc

@@ -82,7 +82,7 @@ BeesContext::dump_status()
 		ofs << "RATES:\n";
 		ofs << "\t" << avg_rates << "\n";
 
-		ofs << "THREADS (work queue " << TaskMaster::get_queue_count() << " tasks, " << TaskMaster::get_thread_count() << " workers):\n";
+		ofs << "THREADS (work queue " << TaskMaster::get_queue_count() << " of " << Task::instance_count() << " tasks, " << TaskMaster::get_thread_count() << " workers):\n";
 		for (auto t : BeesNote::get_status()) {
 			ofs << "\ttid " << t.first << ": " << t.second << "\n";
 		}