jsoncpp: Add headers to help CMake include in-source jsoncpp headers

Add cm_jsoncpp_value.h and cm_jsoncpp_writer.h headers to include the
CMake-provided copy of the json/value.h and json/writer.h headers from
CMake sources.

Utilities/cm_jsoncpp_value.h

@@ -0,0 +1,18 @@
+/*============================================================================
+  CMake - Cross Platform Makefile Generator
+  Copyright 2000-2015 Kitware, Inc., Insight Software Consortium
+
+  Distributed under the OSI-approved BSD License (the "License");
+  see accompanying file Copyright.txt for details.
+
+  This software is distributed WITHOUT ANY WARRANTY; without even the
+  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the License for more information.
+============================================================================*/
+#ifndef cm_jsoncpp_value_h
+#define cm_jsoncpp_value_h
+
+/* Use the jsoncpp library configured for CMake.  */
+#include <cmjsoncpp/include/json/value.h>
+
+#endif

Utilities/cm_jsoncpp_writer.h

@@ -0,0 +1,18 @@
+/*============================================================================
+  CMake - Cross Platform Makefile Generator
+  Copyright 2000-2015 Kitware, Inc., Insight Software Consortium
+
+  Distributed under the OSI-approved BSD License (the "License");
+  see accompanying file Copyright.txt for details.
+
+  This software is distributed WITHOUT ANY WARRANTY; without even the
+  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the License for more information.
+============================================================================*/
+#ifndef cm_jsoncpp_writer_h
+#define cm_jsoncpp_writer_h
+
+/* Use the jsoncpp library configured for CMake.  */
+#include <cmjsoncpp/include/json/writer.h>
+
+#endif