Remove configure-time setting of DEFAULT_NATPMP

Default to false.

src/mapport.h

@@ -11,11 +11,7 @@ static constexpr bool DEFAULT_UPNP = USE_UPNP;
 static constexpr bool DEFAULT_UPNP = false;
 #endif // USE_UPNP
 
-#ifdef USE_NATPMP
-static constexpr bool DEFAULT_NATPMP = USE_NATPMP;
-#else
 static constexpr bool DEFAULT_NATPMP = false;
-#endif // USE_NATPMP
 
 enum MapPortProtoFlag : unsigned int {
     NONE = 0x00,