Replacing usleep with px4_usleep

This is a step towards isolating time from the system.

src/modules/simulator/airspeedsim/airspeedsim.cpp

@@ -271,7 +271,7 @@ AirspeedSim::read(cdev::file_t *filp, char *buffer, size_t buflen)
 		}
 
 		/* wait for it to complete */
-		usleep(_conversion_interval);
+		px4_usleep(_conversion_interval);
 
 		/* run the collection phase */
 		if (OK != collect()) {

src/modules/simulator/gpssim/gpssim.cpp

@@ -198,7 +198,7 @@ GPSSIM::~GPSSIM()
 	/* spin waiting for the task to stop */
 	for (unsigned i = 0; (i < 10) && (_task != -1); i++) {
 		/* give it another 100ms */
-		usleep(100000);
+		px4_usleep(100000);
 	}
 
 	/* well, kill it anyway, though this will probably crash */
@@ -301,7 +301,7 @@ GPSSIM::receive(int timeout)
 
 	} else {
 
-		usleep(timeout);
+		px4_usleep(timeout);
 		return 0;
 	}
 }
@@ -371,7 +371,7 @@ GPSSIM::print_info()
 		print_message(_report_gps_pos);
 	}
 
-	usleep(100000);
+	px4_usleep(100000);
 }
 
 void

src/modules/simulator/simulator.cpp

@@ -220,7 +220,7 @@ extern "C" {
 						break;
 
 					} else {
-						usleep(100000);
+						px4_usleep(100000);
 					}
 				}
 

src/modules/simulator/simulator_mavlink.cpp

@@ -336,7 +336,7 @@ void Simulator::handle_message(mavlink_message_t *msg, bool publish)
 					unsigned usleep_delay = (sysdelay - min_delay) / _realtime_factor;
 
 					// extend by the realtime factor to avoid drift
-					usleep(usleep_delay);
+					px4_usleep(usleep_delay);
 					hrt_stop_delay_delta(exact_delay);
 					px4_sim_stop_delay();
 				}
@@ -838,7 +838,7 @@ void Simulator::pollForMAVLinkMessages(bool publish, int udp_port)
 		if (pret < 0) {
 			PX4_WARN("simulator mavlink: poll error %d, %d", pret, errno);
 			// sleep a bit before next try
-			usleep(100000);
+			px4_usleep(100000);
 			continue;
 		}