delete px4_includes.h header and update boards/ to use syslog

src/drivers/distance_sensor/leddar_one/leddar_one.cpp

@@ -36,6 +36,7 @@
 #include <px4_getopt.h>
 #include <px4_defines.h>
 
+#include <stdlib.h>
 #include <string.h>
 #include <termios.h>
 

src/drivers/distance_sensor/ll40ls/LidarLitePWM.cpp

@@ -122,7 +122,7 @@ void LidarLitePWM::print_info()
 	perf_print_counter(_sample_perf);
 	perf_print_counter(_read_errors);
 	perf_print_counter(_sensor_zero_resets);
-	warnx("poll interval:  %u ticks", getMeasureTicks());
+	PX4_INFO("poll interval:  %u ticks", getMeasureTicks());
 
 	print_message(_range);
 }

src/drivers/distance_sensor/ulanding/ulanding.cpp

@@ -303,8 +303,6 @@ Radar::task_main_trampoline(int argc, char *argv[])
 int
 Radar::start()
 {
-	ASSERT(_task_handle == -1);
-
 	/* start the task */
 	_task_handle = px4_task_spawn_cmd("ulanding_radar",
 					  SCHED_DEFAULT,