Replaced the floating point macrodef constants with constexpr double in the case of C++.

Co-Authored-By: Matthijs Kooijman <matthijs@stdin.nl>

Author: KOLANICH

cores/arduino/Arduino.h

@@ -37,12 +37,27 @@
 
 #include "binary.h"
 
+#if defined(__cplusplus)
+constexpr double PI = 3.1415926535897932384626433832795,
+HALF_PI = 1.5707963267948966192313216916398,
+TWO_PI = 6.283185307179586476925286766559,
+DEG_TO_RAD = 0.017453292519943295769236907684886,
+RAD_TO_DEG = 57.295779513082320876798154814105,
+EULER = 2.718281828459045235360287471352;
+#define PI PI
+#define HALF_PI HALF_PI
+#define TWO_PI TWO_PI
+#define DEG_TO_RAD DEG_TO_RAD
+#define RAD_TO_DEG RAD_TO_DEG
+#define EULER EULER
+#else
 #define PI 3.1415926535897932384626433832795
 #define HALF_PI 1.5707963267948966192313216916398
 #define TWO_PI 6.283185307179586476925286766559
 #define DEG_TO_RAD 0.017453292519943295769236907684886
 #define RAD_TO_DEG 57.295779513082320876798154814105
 #define EULER 2.718281828459045235360287471352
+#endif
 
 #ifdef __cplusplus
 extern "C"{