Remove account_idle

Six years ago this function was added/emptied but it hasn't had anything
added to give it a purpose in life so it seems like a good time to
remove it.

include/seastar/core/reactor.hh

@@ -382,7 +382,6 @@ private:
     task_queue* pop_active_task_queue(sched_clock::time_point now);
     void insert_activating_task_queues();
     void account_runtime(task_queue& tq, sched_clock::duration runtime);
-    void account_idle(sched_clock::duration idletime);
     void allocate_scheduling_group_specific_data(scheduling_group sg, unsigned long key_id);
     future<> rename_scheduling_group_specific_data(scheduling_group sg);
     future<> init_scheduling_group(scheduling_group sg, sstring name, sstring shortname, float shares);

src/core/reactor.cc

@@ -1006,11 +1006,6 @@ reactor::account_runtime(task_queue& tq, sched_clock::duration runtime) {
     tq._runtime += runtime;
 }
 
-void
-reactor::account_idle(sched_clock::duration runtime) {
-    // anything to do here?
-}
-
 struct reactor::task_queue::indirect_compare {
     bool operator()(const task_queue* tq1, const task_queue* tq2) const {
         return tq1->_vruntime < tq2->_vruntime;
@@ -3252,7 +3247,6 @@ int reactor::do_run() {
         if (check_for_work()) {
             if (idle) {
                 _total_idle += idle_end - idle_start;
-                account_idle(idle_end - idle_start);
                 idle_start = idle_end;
                 idle = false;
             }