Put a single event on the recycle queue initially to avoid runtime calloc

Author: erlingrj

core/reactor_common.c

@@ -549,6 +549,14 @@ void _lf_initialize_timers(environment_t* env) {
             _lf_initialize_timer(env, env->timer_triggers[i]);
         }
     }
+    
+    // Create an extra event and put it on the recycle queue. 
+    // An LF program with n timers require n+1 events and the last event 
+    // needs to be initialized to the event recycle queue.
+    if (env->timer_triggers_size > 0) {
+        event_t *e = _lf_get_new_event(env);
+        _lf_recycle_event(env, e);
+    }
 }
 
 /**