SITL: Added SIM_ENGINE_FAIL to define failed motor

libraries/SITL/SITL.cpp

@@ -90,6 +90,7 @@ const AP_Param::GroupInfo SITL::var_info[] = {
     AP_GROUPINFO("ACC2_BIAS",     57, SITL,  accel2_bias, 0),
     AP_GROUPINFO("GPS_NOISE",     58, SITL,  gps_noise, 0),
     AP_GROUPINFO("GP2_GLITCH",    59, SITL,  gps2_glitch,  0),
+    AP_GROUPINFO("ENGINE_FAIL",   60, SITL,  engine_fail,  0),
     AP_GROUPEND
 };
 

libraries/SITL/SITL.h

@@ -91,6 +91,7 @@ public:
     AP_Float drift_speed; // degrees/second/minute
     AP_Float drift_time;  // period in minutes
     AP_Float engine_mul;  // engine multiplier
+    AP_Int8  engine_fail; // engine servo to fail (0-7)
     AP_Int8  gps_disable; // disable simulated GPS
     AP_Int8  gps2_enable; // enable 2nd simulated GPS
     AP_Int8  gps_delay;   // delay in samples