Use OS independent API for task creation/deletion

Calls to task_delete and task_spawn_cmd are now
px4_task_delete and px4_task_spawn_cmd respectively.

The px4_tasks.h header was added to the affected files
and incusions of nuttx/config.h were removed.

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

src/modules/mc_pos_control_multiplatform/mc_pos_control_start_nuttx.cpp

@@ -36,6 +36,7 @@
  *
  * @author Thomas Gubler <thomasgubler@gmail.com>
  */
+#include <px4_tasks.h>
 #include <string.h>
 #include <cstdlib>
 #include <systemlib/err.h>
@@ -68,7 +69,7 @@ int mc_pos_control_m_main(int argc, char *argv[])
 
 		task_should_exit = false;
 
-		daemon_task = task_spawn_cmd("mc_pos_control_m",
+		daemon_task = px4_task_spawn_cmd("mc_pos_control_m",
 				       SCHED_DEFAULT,
 				       SCHED_PRIORITY_MAX - 5,
 				       2500,