fix isspace is not a member of std with Visual Studio 2017

Yoann Long · mrtazz · commit 8142fc8fc1e8 · 2017-09-19T22:15:24.000+02:00
diff --git a/include/restclient-cpp/helpers.h b/include/restclient-cpp/helpers.h
@@ -10,6 +10,7 @@
 #define INCLUDE_RESTCLIENT_CPP_HELPERS_H_
 
 #include <string>
+#include <cctype>
 #include <algorithm>
 #include <functional>
 
