Better fix for M_PI definition

Just use #define _USE_MATH_DEFINES for cmath

extensions/advanced_ballistics/AdvancedBallistics.cpp

@@ -5,10 +5,6 @@
 #include <unordered_map>
 #include <random>
 
-//Guard for M_PI ???? ref https://github.com/acemod/ACE3/pull/2382
-#ifndef M_PI
-    #define M_PI 3.14159265358979323846f
-#endif
 
 #define GRAVITY 9.80665f
 #define ABSOLUTE_ZERO_IN_CELSIUS -273.15f

extensions/common/shared.hpp

@@ -1,5 +1,9 @@
 #pragma once
 
+//_USE_MATH_DEFINES + cmath needs to be first or M_PI won't be defined in VS2015
+#define _USE_MATH_DEFINES
+#include <cmath>
+
 #include "targetver.h"
 #include <assert.h>
 #include <stdio.h>
@@ -11,7 +15,6 @@
 #include <map>
 #include <unordered_map>
 #include <memory>
-#include <cmath>
 #include <cstdint>
 #include <streambuf>
 #include "ace_version.hpp"