Merge #10914: Add missing lock in CScheduler::AreThreadsServicingQueue()

a56f8b0 Add missing lock in CScheduler::AreThreadsServicingQueue() (Matt Corallo)

Pull request description:

  Not an actual bug as this is only used in asserts right now, but
  nice to not have a missing lock.

Tree-SHA512: 7e542b150a0be716783e196493d239f2ad15e5376abf54b67d735dc3ef1b10849c090337b849f530c9f7497ddcfb8389b47d64a5dcf6382b7d38838f88cc1100

src/scheduler.cpp

@@ -141,6 +141,7 @@ size_t CScheduler::getQueueInfo(boost::chrono::system_clock::time_point &first,
 }
 
 bool CScheduler::AreThreadsServicingQueue() const {
+    boost::unique_lock<boost::mutex> lock(newTaskMutex);
     return nThreadsServicingQueue;
 }