PlaylistCommands: remove redundant playlist_load_spl() call

This case is handled already by playlist_open_in_playlist_dir() (via
playlist_mapper_open()).  And the call didn't work anyway.

src/PlaylistSave.cxx

@@ -99,32 +99,3 @@ spl_save_playlist(const char *name_utf8, const playlist &playlist)
 {
 	return spl_save_queue(name_utf8, playlist.queue);
 }
-
-bool
-playlist_load_spl(struct playlist &playlist, PlayerControl &pc,
-		  const char *name_utf8,
-		  unsigned start_index, unsigned end_index,
-		  Error &error)
-{
-	PlaylistFileContents contents = LoadPlaylistFile(name_utf8, error);
-	if (contents.empty() && error.IsDefined())
-		return false;
-
-	if (end_index > contents.size())
-		end_index = contents.size();
-
-	const SongLoader loader(nullptr, nullptr);
-	Error error2;
-
-	for (unsigned i = start_index; i < end_index; ++i) {
-		const auto &uri_utf8 = contents[i];
-
-		unsigned id = playlist.AppendURI(pc, loader, uri_utf8.c_str(),
-						 error2);
-		if (id == 0)
-			FormatError(error2, "can't add file \"%s\"",
-				    uri_utf8.c_str());
-	}
-
-	return true;
-}

src/PlaylistSave.hxx

@@ -48,14 +48,4 @@ spl_save_queue(const char *name_utf8, const Queue &queue);
 PlaylistResult
 spl_save_playlist(const char *name_utf8, const playlist &playlist);
 
-/**
- * Loads a stored playlist file, and append all songs to the global
- * playlist.
- */
-bool
-playlist_load_spl(struct playlist &playlist, PlayerControl &pc,
-		  const char *name_utf8,
-		  unsigned start_index, unsigned end_index,
-		  Error &error);
-
 #endif

src/command/PlaylistCommands.cxx

@@ -74,23 +74,7 @@ handle_load(Client &client, int argc, char *argv[])
 				      client.player_control, loader, error))
 		return print_error(client, error);
 
-	if (playlist_load_spl(client.playlist, client.player_control,
-			      argv[1], start_index, end_index,
-			      error))
-		return CommandResult::OK;
-
-	if (error.IsDomain(playlist_domain) &&
-	    PlaylistResult(error.GetCode()) == PlaylistResult::BAD_NAME) {
-		/* the message for BAD_NAME is confusing when the
-		   client wants to load a playlist file from the music
-		   directory; patch the Error object to show "no such
-		   playlist" instead */
-		Error error2(playlist_domain, int(PlaylistResult::NO_SUCH_LIST),
-			     error.GetMessage());
-		error = std::move(error2);
-	}
-
-	return print_error(client, error);
+	return CommandResult::OK;
 }
 
 CommandResult