Adds iperf timeout for bandwith measurements.

measurement_main.py

                     tcp_algo[congestion_control_index],
                 ]
                 is_measurement_done = False
-                while not is_measurement_done:
+                iperf_return = 0
+                while not is_measurement_done or iperf_return != 0:
                     try:
                         try:
-                            subprocess.call(iperf_command, timeout=float(time) + TIMEOUT_OFFSET)
+                            iperf_return = subprocess.call(iperf_command, timeout=float(time) + TIMEOUT_OFFSET)
                             is_measurement_done = True
                         except:
                             print_message("iPerf timed out. Retry...")
                 )
                 sleep(2)
                 is_measurement_done = False
-                while not is_measurement_done:
+                iperf_return = 0
+                while not is_measurement_done or iperf_return != 0:
                     try:
                         try:
-                            subprocess.call(iperf_command, timeout=float(time) + TIMEOUT_OFFSET)
+                            iperf_return = subprocess.call(iperf_command, timeout=float(time) + TIMEOUT_OFFSET)
                             is_measurement_done = True
                         except:
                             print_message("iPerf timed out. Retry...")