Fixed some new code smells

include/fc/thread/parallel.hpp

@@ -49,7 +49,7 @@ namespace fc {
    private:
       class ticket_guard {
       public:
-         ticket_guard( boost::atomic<future<void>*>& latch );
+         explicit ticket_guard( boost::atomic<future<void>*>& latch );
          ~ticket_guard();
          void wait_for_my_turn();
       private:

include/fc/thread/thread.hpp

@@ -25,6 +25,8 @@ namespace fc {
     */
    class thread_idle_notifier {
    public:
+      virtual ~thread_idle_notifier() {}
+
       /** This method is called when the thread is idle. If it returns a
        *  task_base it will be queued and executed immediately.
        *  @return a task to execute, or nullptr

src/asio.cpp

@@ -119,7 +119,7 @@ namespace fc {
        {
           // the default was not set by the configuration. Determine a good
           // number of threads. Minimum of 8, maximum of hardware_concurrency
-          num_io_threads = std::max( boost::thread::hardware_concurrency(), 8u );
+          num_io_threads = std::max( boost::thread::hardware_concurrency(), 8U );
        }
 
        for( uint16_t i = 0; i < num_io_threads; ++i )

src/thread/parallel.cpp

@@ -32,8 +32,6 @@
 
 namespace fc {
    namespace detail {
-      class pool_impl;
-
       class idle_notifier_impl : public thread_idle_notifier
       {
       public:
@@ -49,6 +47,8 @@ namespace fc {
             is_idle.store( copy.is_idle.load() );
          }
 
+         virtual ~idle_notifier_impl() {}
+
          virtual task_base* idle();
          virtual void       busy()
          {
@@ -63,7 +63,7 @@ namespace fc {
       class pool_impl
       {
       public:
-         pool_impl( const uint16_t num_threads )
+         explicit pool_impl( const uint16_t num_threads )
             : idle_threads( 2 * num_threads ), waiting_tasks( 200 )
          {
             notifiers.resize( num_threads );

src/thread/thread_d.hpp

@@ -19,7 +19,7 @@ namespace fc {
     namespace detail {
        class idle_guard {
        public:
-          idle_guard( thread_d* t );
+          explicit idle_guard( thread_d* t );
           ~idle_guard();
        private:
           thread_idle_notifier* notifier;