Plane: use labs for int32 values

ArduPlane/ArduPlane.cpp

@@ -382,7 +382,7 @@ void Plane::airspeed_ratio_update(void)
         // never coming up again
         return;
     }
-    if (abs(ahrs.roll_sensor) > roll_limit_cd ||
+    if (labs(ahrs.roll_sensor) > roll_limit_cd ||
         ahrs.pitch_sensor > aparm.pitch_limit_max_cd ||
         ahrs.pitch_sensor < pitch_limit_min_cd) {
         // don't calibrate when going beyond normal flight envelope

ArduPlane/commands_logic.cpp

@@ -615,7 +615,7 @@ bool Plane::verify_loiter_to_alt()
           We use 10 degrees of slop so that we can handle 100
           degrees/second of yaw
         */
-        if (abs(heading_err_cd) <= 1000) {
+        if (labs(heading_err_cd) <= 1000) {
             //Want to head in a straight line from _here_ to the next waypoint.
             //DON'T want to head in a line from the center of the loiter to 
             //the next waypoint.
@@ -655,7 +655,7 @@ bool Plane::verify_continue_and_change_alt()
         return true;
     }    
     //don't care if we're climbing or descending
-    else if (abs(adjusted_altitude_cm() - next_WP_loc.alt) <= 500) {
+    else if (labs(adjusted_altitude_cm() - next_WP_loc.alt) <= 500) {
         return true;
     }
    

ArduPlane/takeoff.cpp

@@ -61,7 +61,7 @@ bool Plane::auto_takeoff_check(void)
     // Check aircraft attitude for bad launch
     if (ahrs.pitch_sensor <= -3000 ||
         ahrs.pitch_sensor >= 4500 ||
-        abs(ahrs.roll_sensor) > 3000) {
+        labs(ahrs.roll_sensor) > 3000) {
         gcs_send_text_fmt(PSTR("Bad Launch AUTO"));
         goto no_launch;
     }