AP_Airspeed: fixed some warnings

libraries/AP_Airspeed/AP_Airspeed.cpp

@@ -136,7 +136,6 @@ void AP_Airspeed::calibrate()
 {
     float sum = 0;
     uint8_t count = 0;
-    uint8_t c;
     if (!_enable) {
         return;
     }

libraries/AP_Airspeed/AP_Airspeed.h

@@ -42,9 +42,9 @@ public:
     // constructor
     AP_Airspeed(const AP_Vehicle::FixedWing &parms) : 
         _EAS2TAS(1.0f),
+        _healthy(false),
         _calibration(parms),
-        analog(_pin),
-        _healthy(false)
+        analog(_pin)
     {
 		AP_Param::setup_object_defaults(this, var_info);
     };