Plane: use singletons in AP_Arming

ArduPlane/AP_Arming.cpp

@@ -94,8 +94,8 @@ bool AP_Arming_Plane::ins_checks(bool display_failure)
     // additional plane specific checks
     if ((checks_to_perform & ARMING_CHECK_ALL) ||
         (checks_to_perform & ARMING_CHECK_INS)) {
-        if (!ahrs.healthy()) {
+        if (!AP::ahrs().healthy()) {
-            const char *reason = ahrs.prearm_failure_reason();
+            const char *reason = AP::ahrs().prearm_failure_reason();
             if (reason == nullptr) {
                 reason = "AHRS not healthy";
             }

ArduPlane/AP_Arming.h

@@ -8,9 +8,8 @@
 class AP_Arming_Plane : public AP_Arming
 {
 public:
-    AP_Arming_Plane(const AP_AHRS &ahrs_ref, Compass &compass,
+    AP_Arming_Plane()
-                    const AP_BattMonitor &battery)
+        : AP_Arming()
-        : AP_Arming(ahrs_ref, compass, battery)
     {
         AP_Param::setup_object_defaults(this, var_info);
     }

ArduPlane/Plane.h

@@ -747,7 +747,7 @@ private:
 #endif
 
     // Arming/Disarming mangement class
-    AP_Arming_Plane arming{ahrs, compass, battery};
+    AP_Arming_Plane arming;
 
     AP_Param param_loader {var_info};