Use C++ standard headers.

Author: connormanning

src/lib_json/json_writer.cpp

@@ -12,27 +12,27 @@
 #include <sstream>
 #include <utility>
 #include <set>
-#include <assert.h>
-#include <math.h>
-#include <stdio.h>
-#include <string.h>
+#include <cassert>
+#include <cstring>
+#include <cstdio>
 
 #if defined(_MSC_VER) && _MSC_VER < 1500 // VC++ 8.0 and below
 #include <float.h>
 #define isfinite _finite
 #define snprintf _snprintf
+#elif defined(__sun) && defined(__SVR4) //Solaris
+#include <ieeefp.h>
+#define isfinite finite
+#else
+#include <cmath>
+#define isfinite std::isfinite
 #endif
 
 #if defined(_MSC_VER) && _MSC_VER >= 1400 // VC++ 8.0
 // Disable warning about strdup being deprecated.
 #pragma warning(disable : 4996)
 #endif
 
-#if defined(__sun) && defined(__SVR4) //Solaris
-#include <ieeefp.h>
-#define isfinite finite
-#endif
-
 namespace Json {
 
 #if __cplusplus >= 201103L