Add ToS Byte to iperf API (#719)

* Add ToS byte to iperf API

* Add function prototype to manual page
diff --git a/src/iperf_api.c b/src/iperf_api.c
index 878c9c4..8bf5296 100755
--- a/src/iperf_api.c
+++ b/src/iperf_api.c
@@ -290,6 +290,12 @@
     return ipt->one_off;
 }
 
+int
+iperf_get_test_tos(struct iperf_test *ipt)
+{
+    return ipt->settings->tos;
+}
+
 /************** Setter routines for some fields inside iperf_test *************/
 
 void
@@ -467,6 +473,12 @@
     ipt->one_off = one_off;
 }
 
+void
+iperf_set_test_tos(struct iperf_test *ipt, int tos)
+{
+    ipt->settings->tos = tos;
+}
+
 /********************** Get/set test protocol structure ***********************/
 
 struct protocol *
diff --git a/src/iperf_api.h b/src/iperf_api.h
index 3a5df03..ddd002b 100755
--- a/src/iperf_api.h
+++ b/src/iperf_api.h
@@ -115,6 +115,7 @@
 char*	iperf_get_test_bind_address ( struct iperf_test* ipt );
 int	iperf_get_test_udp_counters_64bit( struct iperf_test* ipt );
 int	iperf_get_test_one_off( struct iperf_test* ipt );
+int iperf_get_test_tos( struct iperf_test* ipt );
 
 /* Setter routines for some fields inside iperf_test. */
 void	iperf_set_verbose( struct iperf_test* ipt, int verbose );
@@ -141,6 +142,7 @@
 void	iperf_set_test_bind_address( struct iperf_test* ipt, char *bind_address );
 void	iperf_set_test_udp_counters_64bit( struct iperf_test* ipt, int udp_counters_64bit );
 void	iperf_set_test_one_off( struct iperf_test* ipt, int one_off );
+void    iperf_set_test_tos( struct iperf_test* ipt, int tos );
 
 /**
  * exchange_parameters - handles the param_Exchange part for client
diff --git a/src/libiperf.3 b/src/libiperf.3
index 674d95f..078b7be 100644
--- a/src/libiperf.3
+++ b/src/libiperf.3
@@ -33,6 +33,7 @@
     void iperf_set_test_json_output( struct iperf_test *t, int json_output );
     int iperf_has_zerocopy( void );
     void iperf_set_test_zerocopy( struct iperf_test* t, int zerocopy );
+    void iperf_set_test_tos( struct iperf_test* t, int tos );
 .fi
 Running a test:
 .nf