Removed extra abstracton layer in systemlib

The calls to task_spawn_cmd, kill_all, and systemreset  were wrappers
around the px4_{task_spawn_cmd|kill_all|systemreset} implementations.

Removed the wrappers and changed all calls to the px4_ equivalents.

NuttX specific code was moved into px4_tasks.h

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

src/platforms/px4_tasks.h

@@ -43,16 +43,26 @@
 #include <stdbool.h>
 
 #ifdef __PX4_ROS
+
 #error "PX4 tasks not supported in ROS"
+
 #elif defined(__PX4_NUTTX)
 typedef int px4_task_t;
 
+/** Default scheduler type */
+#if CONFIG_RR_INTERVAL > 0
+# define SCHED_DEFAULT  SCHED_RR
+#else
+# define SCHED_DEFAULT  SCHED_FIFO
+#endif
+
 #define px4_task_exit(x) _exit(x)
 
 #elif defined(__PX4_POSIX) || defined(__PX4_QURT)
 #include <pthread.h>
 #include <sched.h>
 
+/** Default scheduler type */
 #define SCHED_DEFAULT	SCHED_FIFO
 #ifdef __PX4_LINUX
 #define SCHED_PRIORITY_MAX sched_get_priority_max(SCHED_FIFO)