re-instate Arduino macros for min/max

After discussion with Kirk we agreed that ```that's just the way it is``` in Arduino. Solved the TFLM example support by simply placing this at the top of the example

``` c++
#ifdef min
#undef min
#endif

#ifdef max
#undef max
#endif
```

Author: oclyke

cores/arduino/ard_sup/Arduino_defines.h

@@ -28,8 +28,8 @@
 #undef abs
 #endif // abs
 
-// #define min(a, b) ((a) < (b) ? (a) : (b))
-// #define max(a, b) ((a) > (b) ? (a) : (b))
+#define min(a, b) ((a) < (b) ? (a) : (b))
+#define max(a, b) ((a) > (b) ? (a) : (b))
 #define abs(x) ((x) > 0 ? (x) : -(x))
 #define constrain(amt, low, high) ((amt) < (low) ? (low) : ((amt) > (high) ? (high) : (amt)))
 #define round(x) ((x) >= 0 ? (long)((x) + 0.5) : (long)((x)-0.5))