src: remove declarations for missing functions

Backport-PR-URL: #20456
PR-URL: #18134
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>

src/node_http2.h

@@ -1048,24 +1048,6 @@ class Http2Session : public AsyncWrap {
       int lib_error_code,
       void* user_data);
 
-
-  static inline ssize_t OnStreamReadFD(
-      nghttp2_session* session,
-      int32_t id,
-      uint8_t* buf,
-      size_t length,
-      uint32_t* flags,
-      nghttp2_data_source* source,
-      void* user_data);
-  static inline ssize_t OnStreamRead(
-      nghttp2_session* session,
-      int32_t id,
-      uint8_t* buf,
-      size_t length,
-      uint32_t* flags,
-      nghttp2_data_source* source,
-      void* user_data);
-
   struct Callbacks {
     inline explicit Callbacks(bool kHasGetPaddingCallback);
     inline ~Callbacks();