Readd some overzealously removed code

Author: baylesj

include/json/autolink.h

@@ -30,6 +30,22 @@
 /// Remarks: it is automatically defined in the generated amalgamated header.
 // #define JSON_IS_AMALGAMATION
 
+// Export macros for DLL visibility
+#if defined(JSON_DLL_BUILD)
+#if defined(_MSC_VER) || defined(__MINGW32__)
+#define JSON_API __declspec(dllexport)
+#define JSONCPP_DISABLE_DLL_INTERFACE_WARNING
+#elif defined(__GNUC__) || defined(__clang__)
+#define JSON_API __attribute__((visibility("default")))
+#endif // if defined(_MSC_VER)
+
+#elif defined(JSON_DLL)
+#if defined(_MSC_VER) || defined(__MINGW32__)
+#define JSON_API __declspec(dllimport)
+#define JSONCPP_DISABLE_DLL_INTERFACE_WARNING
+#endif // if defined(_MSC_VER)
+#endif // ifdef JSON_DLL_BUILD
+
 #if !defined(JSON_API)
 #define JSON_API
 #endif

include/json/config.h

@@ -6,7 +6,7 @@
 #ifndef JSON_JSON_H_INCLUDED
 #define JSON_JSON_H_INCLUDED
 
-#include "autolink.h"
+#include "config.h"
 #include "json_features.h"
 #include "reader.h"
 #include "value.h"

include/json/json.h

@@ -21,7 +21,6 @@ project(
 jsoncpp_headers = [
   'include/json/allocator.h',
   'include/json/assertions.h',
-  'include/json/autolink.h',
   'include/json/config.h',
   'include/json/json_features.h',
   'include/json/forwards.h',