APM: Fixed bug where landing_pitch wasnt initialized properly

this adds a new LAND_PITCH_CD parameter to control the landing pitch
when an airspeed sensor is not being used

ArduPlane/ArduPlane.pde

@@ -476,8 +476,6 @@ static bool takeoff_complete    = true;
 static bool	land_complete;
 // Altitude threshold to complete a takeoff command in autonomous modes.  Centimeters
 static int32_t	takeoff_altitude;
-// Pitch to hold during landing command in the no airspeed sensor case.  Hundredths of a degree
-static int16_t			landing_pitch;
 // Minimum pitch to hold during takeoff command execution.  Hundredths of a degree
 static int16_t			takeoff_pitch;
 
@@ -1014,7 +1012,7 @@ static void update_current_flight_mode(void)
 				}else{
 					calc_nav_pitch();               // calculate nav_pitch just to use for calc_throttle
 					calc_throttle();                // throttle based on altitude error
-					nav_pitch = landing_pitch;      // pitch held constant
+					nav_pitch = g.land_pitch_cd;      // pitch held constant
 				}
 
 				if (land_complete) {

ArduPlane/Parameters.h

@@ -69,6 +69,7 @@ public:
         k_param_log_last_filenumber,		// *** Deprecated - remove with next eeprom number change
         k_param_reset_switch_chan,
         k_param_manual_level,
+		k_param_land_pitch_cd,
 
 		// 110: Telemetry control
 		//
@@ -337,6 +338,7 @@ public:
     AP_Int8		reset_switch_chan;
     AP_Int8		manual_level;
     AP_Int16    airspeed_cruise_cm;
+	AP_Int16	land_pitch_cd;
     AP_Int16    min_gndspeed;
     AP_Int16    pitch_trim;
     AP_Int16    RTL_altitude;
@@ -456,6 +458,7 @@ public:
         reset_switch_chan		(0),
         manual_level			(MANUAL_LEVEL),
         airspeed_cruise_cm      (AIRSPEED_CRUISE_CM),
+		land_pitch_cd			(0),
         min_gndspeed            (MIN_GNDSPEED_CM),
         pitch_trim              (0),
         RTL_altitude            (ALT_HOLD_HOME_CM),

ArduPlane/Parameters.pde

@@ -65,6 +65,13 @@ static const AP_Param::Info var_info[] PROGMEM = {
 	// @User: Advanced
 	GSCALAR(manual_level,           "MANUAL_LEVEL"),
 
+	// @Param: land_pitch_cd
+	// @DisplayName: Landing Pitch
+	// @Description: Used in autoland for planes without airspeed sensors in hundredths of a degree
+	// @Units: centi-Degrees
+	// @User: Advanced
+	GSCALAR(land_pitch_cd,          "land_pitch_cd"),
+
     // @Param: XTRK_GAIN_SC
 	// @DisplayName: Crosstrack Gain
 	// @Description: The scale between distance off the line and angle to meet the line (in Degrees * 100)