Set default value of iteration/subiteration to -1, so it's not shown by default

src/core/sched_ctx.c

@@ -501,8 +501,8 @@ struct _starpu_sched_ctx* _starpu_create_sched_ctx(struct starpu_sched_policy *p
 	_starpu_barrier_counter_init(&sched_ctx->ready_tasks_barrier, 0);
 
 	sched_ctx->ready_flops = 0.0;
-	sched_ctx->iteration = 0;
-	sched_ctx->subiteration = 0;
+	sched_ctx->iteration = -1;
+	sched_ctx->subiteration = -1;
 	sched_ctx->main_master = -1;
 	sched_ctx->perf_arch.devices = NULL;
 	sched_ctx->perf_arch.ndevices = 0;

src/core/sched_ctx.h

@@ -70,7 +70,7 @@ struct _starpu_sched_ctx
 	double ready_flops;
 
 	/* Iteration number, as advertised by application */
-	unsigned long iteration, subiteration;
+	long iteration, subiteration;
 
 	/* cond to block push when there are no workers in the ctx */
 	starpu_pthread_cond_t no_workers_cond;