Copter: Enable NAV_GUIDED #define to support "guided" in AUTO

ArduCopter/APM_Config.h

@@ -29,7 +29,7 @@
 //#define AC_TERRAIN            DISABLED            // disable terrain library
 //#define PARACHUTE             DISABLED            // disable parachute release to save 1k of flash
 //#define CLI_ENABLED           DISABLED            // disable the CLI (command-line-interface) to save 21K of flash space
-//#define NAV_GUIDED            DISABLED            // disable external navigation computer ability to control vehicle through MAV_CMD_NAV_GUIDED mission commands
+#define NAV_GUIDED            ENABLED            // disable external navigation computer ability to control vehicle through MAV_CMD_NAV_GUIDED mission commands
 //#define OPTFLOW               DISABLED            // disable optical flow sensor to save 5K of flash space
 //#define FRSKY_TELEM_ENABLED   DISABLED            // disable FRSky telemetry
 //#define ADSB_ENABLED          DISABLED            // disable ADSB support