Fixed conflicts with isnan() and isinf() macros (fixes #752)

src/ArduinoJson/Polyfills/math.hpp

@@ -6,14 +6,22 @@
 
 namespace ArduinoJson {
 namespace Internals {
+
+// Some libraries #define isnan() and isinf() so we need to check before
+// using this name
+
+#ifndef isnan
 template <typename T>
 bool isnan(T x) {
   return x != x;
 }
+#endif
 
+#ifndef isinf
 template <typename T>
 bool isinf(T x) {
   return x != 0.0 && x * 2 == x;
 }
+#endif
 }  // namespace Internals
 }  // namespace ArduinoJson