Added #ifndef DELTA wrapper to float delta

Marlin/Marlin_main.cpp

 //===========================================================================
 const char axis_codes[NUM_AXIS] = {'X', 'Y', 'Z', 'E'};
 static float destination[NUM_AXIS] = {  0.0, 0.0, 0.0, 0.0};
+
 static float delta[3] = {0.0, 0.0, 0.0};
+#endif
+
 static float offset[3] = {0.0, 0.0, 0.0};
 static bool home_all_axis = true;
 static float feedrate = 1500.0, next_feedrate, saved_feedrate;