COMP:  Use C++11 override directly

The override support in C++11 is required so avoid aliasing
this feature.  Compilers that do not support the override keyword
are no longer supported.
diff --git a/include/json/config.h b/include/json/config.h
index a36ca15..5049c73 100644
--- a/include/json/config.h
+++ b/include/json/config.h
@@ -89,12 +89,11 @@
 // In c++11 the override keyword allows you to explicitly define that a function
 // is intended to override the base-class version.  This makes the code more
 // manageable and fixes a set of common hard-to-find bugs.
+#define JSONCPP_OVERRIDE override    // Define maintained for backwards compatibility of external tools.  C++11 should be used directly in JSONCPP
 #if __cplusplus >= 201103L
-#define JSONCPP_OVERRIDE override
 #define JSONCPP_NOEXCEPT noexcept
 #define JSONCPP_OP_EXPLICIT explicit
 #elif defined(_MSC_VER) && _MSC_VER > 1600 && _MSC_VER < 1900
-#define JSONCPP_OVERRIDE override
 #define JSONCPP_NOEXCEPT throw()
 #if _MSC_VER >= 1800 // MSVC 2013
 #define JSONCPP_OP_EXPLICIT explicit
@@ -102,11 +101,9 @@
 #define JSONCPP_OP_EXPLICIT
 #endif
 #elif defined(_MSC_VER) && _MSC_VER >= 1900
-#define JSONCPP_OVERRIDE override
 #define JSONCPP_NOEXCEPT noexcept
 #define JSONCPP_OP_EXPLICIT explicit
 #else
-#define JSONCPP_OVERRIDE
 #define JSONCPP_NOEXCEPT throw()
 #define JSONCPP_OP_EXPLICIT
 #endif