Delete JSONCPP_DEPRECATED, use [[deprecated]] instead. (#978)

* delete JSONCPP_DEPRECATED, use [[deprecated]]

* add pragma warning(disable:4996)

* add error C2416

* update

* update

* update
diff --git a/include/json/value.h b/include/json/value.h
index 30ce89f..a478848 100644
--- a/include/json/value.h
+++ b/include/json/value.h
@@ -564,7 +564,7 @@
   //# endif
 
   /// \deprecated Always pass len.
-  JSONCPP_DEPRECATED("Use setComment(String const&) instead.")
+  [[deprecated("Use setComment(String const&) instead.")]]
   void setComment(const char* comment, CommentPlacement placement) {
     setComment(String(comment, strlen(comment)), placement);
   }
@@ -750,7 +750,7 @@
   /// objectValue.
   /// \deprecated This cannot be used for UTF-8 strings, since there can be
   /// embedded nulls.
-  JSONCPP_DEPRECATED("Use `key = name();` instead.")
+  [[deprecated("Use `key = name();` instead.")]]
   char const* memberName() const;
   /// Return the member name of the referenced Value, or NULL if it is not an
   /// objectValue.