partially revert 'fix bug for static init'

re: 28836b8

A global instance of a Value (viz. 'null') was a mistake,
but dropping it breaks binary-compatibility. So we will keep it
everywhere except the one platform where it was crashing, ARM.

include/json/value.h

@@ -160,8 +160,11 @@ class JSON_API Value {
   typedef Json::LargestUInt LargestUInt;
   typedef Json::ArrayIndex ArrayIndex;
 
-  static const Value& null;  ///< We regret this reference to a global instance; prefer the simpler Value().
-  static const Value& nullRef;  ///< just a kludge for binary-compatibility; same as null
+  static const Value& nullRef;
+#if !defined(__ARMEL__)
+  /// \deprecated This exists for binary compatibility only. Use nullRef.
+  static const Value null;
+#endif
   /// Minimum signed integer value that can be stored in a Json::Value.
   static const LargestInt minLargestInt;
   /// Maximum signed integer value that can be stored in a Json::Value.

src/lib_json/json_value.cpp

@@ -29,12 +29,13 @@ namespace Json {
 #if defined(__ARMEL__)
 #define ALIGNAS(byte_alignment) __attribute__((aligned(byte_alignment)))
 #else
+// This exists for binary compatibility only. Use nullRef.
+const Value Value::null;
 #define ALIGNAS(byte_alignment)
 #endif
 static const unsigned char ALIGNAS(8) kNull[sizeof(Value)] = { 0 };
 const unsigned char& kNullRef = kNull[0];
-const Value& Value::null = reinterpret_cast<const Value&>(kNullRef);
-const Value& Value::nullRef = null;
+const Value& Value::nullRef = reinterpret_cast<const Value&>(kNullRef);
 
 const Int Value::minInt = Int(~(UInt(-1) / 2));
 const Int Value::maxInt = Int(UInt(-1) / 2);