Provide JSONCPP_DEPRECATED definitions for clang and gcc

Author: Dani-Hub

include/json/config.h

@@ -70,6 +70,11 @@
 #if defined(_MSC_VER) && _MSC_VER >= 1500 // MSVC 2008
 /// Indicates that the following function is deprecated.
 #define JSONCPP_DEPRECATED(message) __declspec(deprecated(message))
+#elif (defined(__clang__) && __has_attribute(deprecated)) || \
+      (defined(__GNUC__) &&  (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)))
+#define JSONCPP_DEPRECATED(message)  __attribute__ ((deprecated(message)))
+#elif defined(__GNUC__) &&  (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
+#define JSONCPP_DEPRECATED(message)  __attribute__((__deprecated__))
 #endif
 
 #if !defined(JSONCPP_DEPRECATED)