Solves #1108. The default copy constructor of GenericPointer will use the…

Solves #1108. The default copy constructor of GenericPointer will use the allocator of the copied object. The extra copy constructor that takes an allocator as a parameter is distinct if someone really wants to create a copy with a null allocator.

include/rapidjson/pointer.h

@@ -165,7 +165,12 @@ public:
     GenericPointer(const Token* tokens, size_t tokenCount) : allocator_(), ownAllocator_(), nameBuffer_(), tokens_(const_cast<Token*>(tokens)), tokenCount_(tokenCount), parseErrorOffset_(), parseErrorCode_(kPointerParseErrorNone) {}
 
     //! Copy constructor.
-    GenericPointer(const GenericPointer& rhs, Allocator* allocator = 0) : allocator_(allocator), ownAllocator_(), nameBuffer_(), tokens_(), tokenCount_(), parseErrorOffset_(), parseErrorCode_(kPointerParseErrorNone) {
+    GenericPointer(const GenericPointer& rhs) : allocator_(rhs.allocator_), ownAllocator_(), nameBuffer_(), tokens_(), tokenCount_(), parseErrorOffset_(), parseErrorCode_(kPointerParseErrorNone) {
+        *this = rhs;
+    }
+
+    //! Copy constructor.
+    GenericPointer(const GenericPointer& rhs, Allocator* allocator) : allocator_(allocator), ownAllocator_(), nameBuffer_(), tokens_(), tokenCount_(), parseErrorOffset_(), parseErrorCode_(kPointerParseErrorNone) {
         *this = rhs;
     }