AP_Arming: convert to delegates

libraries/AP_Arming/AP_Arming.h

@@ -38,7 +38,7 @@ public:
     };
 
     //for the hacky funciton pointer to gcs_send_text_p
-    typedef void (*gcs_send_t_p)(gcs_severity, const prog_char_t*);
+    typedef DELEGATE_FUNCTION2(void, gcs_severity, const prog_char_t*) gcs_send_t_p;
 
     AP_Arming(const AP_AHRS &ahrs_ref, const AP_Baro &baro, Compass &compass,
               const enum HomeState &home_set, gcs_send_t_p);