[sm130futures] jsoncpp -> extern

This won't build on Windows or Mac OS X yet.

extern/jsoncpp/include/json/forwards.h

@@ -0,0 +1,39 @@
+#ifndef JSON_FORWARDS_H_INCLUDED
+# define JSON_FORWARDS_H_INCLUDED
+
+# include "config.h"
+
+namespace Json {
+
+   // writer.h
+   class FastWriter;
+   class StyledWriter;
+
+   // reader.h
+   class Reader;
+
+   // features.h
+   class Features;
+
+   // value.h
+   typedef int Int;
+   typedef unsigned int UInt;
+   class StaticString;
+   class Path;
+   class PathArgument;
+   class Value;
+   class ValueIteratorBase;
+   class ValueIterator;
+   class ValueConstIterator;
+#ifdef JSON_VALUE_USE_INTERNAL_MAP
+   class ValueAllocator;
+   class ValueMapAllocator;
+   class ValueInternalLink;
+   class ValueInternalArray;
+   class ValueInternalMap;
+#endif // #ifdef JSON_VALUE_USE_INTERNAL_MAP
+
+} // namespace Json
+
+
+#endif // JSON_FORWARDS_H_INCLUDED