sys/benchmark: incl irq.h and fixed output

sys/benchmark/benchmark.c

 /*
- * Copyright (C) 2017 Freie Universität Berlin
+ * Copyright (C) 2017,2018 Freie Universität Berlin
  *
  * This file is subject to the terms and conditions of the GNU Lesser General
  * Public License v2.1. See the file LICENSE in the top level directory for more
@@ -27,6 +27,10 @@ void benchmark_print_time(uint32_t time, unsigned long runs, const char *name)
     uint32_t full = (time / runs);
     uint32_t div  = (time - (full * runs)) / (runs / 1000);
 
-    printf("%11s: %9" PRIu32 "us  ---  %2" PRIu32 ".%03" PRIu32 "us per call\n",
-           name, time, full, div);
+    uint32_t per_sec = (uint32_t)(((uint64_t)1000000UL * runs) / time);
+
+    printf("%25s: %9" PRIu32 "us"
+           "  ---  %2" PRIu32 ".%03" PRIu32 "us per call"
+           "  ---  %9" PRIu32 " calls per sec\n",
+           name, time, full, div, per_sec);
 }

sys/include/benchmark.h

 /*
- * Copyright (C) 2017 Freie Universität Berlin
+ * Copyright (C) 2017,2018 Freie Universität Berlin
  *
  * This file is subject to the terms and conditions of the GNU Lesser
  * General Public License v2.1. See the file LICENSE in the top level
@@ -23,6 +23,7 @@
 
 #include <stdint.h>
 
+#include "irq.h"
 #include "xtimer.h"
 
 #ifdef __cplusplus