c++20: Implicit value sharing of this is deprecated in C++20

Fix the handful of instances.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>
(cherry picked from commit 4d6b21fb40174c3ecdc9e97670dae0dd22ce74a6)

lib/task.cc

@@ -754,7 +754,7 @@ namespace crucible {
 		m_prev_loadavg = getloadavg1();
 
 		if (target && !m_load_tracking_thread) {
-			m_load_tracking_thread = make_shared<thread>([=] () { loadavg_thread_fn(); });
+			m_load_tracking_thread = make_shared<thread>([this] () { loadavg_thread_fn(); });
 			m_load_tracking_thread->detach();
 		}
 	}
@@ -944,7 +944,7 @@ namespace crucible {
 	TaskConsumer::TaskConsumer(const shared_ptr<TaskMasterState> &tms) :
 		m_master(tms)
 	{
-		m_thread = make_shared<thread>([=](){ consumer_thread(); });
+		m_thread = make_shared<thread>([this](){ consumer_thread(); });
 	}
 
 	class BarrierState {