Added function prototype for missing declaration errors with nuttx

src/modules/mc_att_control_multiplatform/mc_att_control_main.cpp

@@ -59,6 +59,7 @@ bool mc_att_control_thread_running = false;     /**< Deamon status flag */
 #if defined(__PX4_ROS)
 int main(int argc, char **argv)
 #else
+int mc_att_control_start_main(int argc, char **argv);  // Prototype for missing declearation error with nuttx
 int mc_att_control_start_main(int argc, char **argv)
 #endif
 {

src/modules/mc_pos_control_multiplatform/mc_pos_control_main.cpp

@@ -51,6 +51,7 @@ bool mc_pos_control_thread_running = false;     /**< Deamon status flag */
 #if defined(__PX4_ROS)
 int main(int argc, char **argv)
 #else
+int mc_pos_control_start_main(int argc, char **argv);  // Prototype for missing declearation error with nuttx
 int mc_pos_control_start_main(int argc, char **argv)
 #endif
 {