PlaylistFile: switch spl_append_uri() arguments

src/PlaylistFile.cxx

@@ -402,7 +402,7 @@ spl_append_song(const char *utf8path, const DetachedSong &song, Error &error)
 }
 
 bool
-spl_append_uri(const char *url, const char *utf8file, Error &error)
+spl_append_uri(const char *utf8file, const char *url, Error &error)
 {
 	if (uri_has_scheme(url)) {
 		return spl_append_song(utf8file, DetachedSong(url),

src/PlaylistFile.hxx

@@ -71,7 +71,7 @@ bool
 spl_append_song(const char *utf8path, const DetachedSong &song, Error &error);
 
 bool
-spl_append_uri(const char *file, const char *utf8file, Error &error);
+spl_append_uri(const char *path_utf8, const char *uri_utf8, Error &error);
 
 bool
 spl_rename(const char *utf8from, const char *utf8to, Error &error);

src/command/PlaylistCommands.cxx

@@ -194,7 +194,7 @@ handle_playlistadd(Client &client, gcc_unused int argc, char *argv[])
 			return CommandResult::ERROR;
 		}
 
-		success = spl_append_uri(uri, playlist, error);
+		success = spl_append_uri(playlist, uri, error);
 	} else {
 #ifdef ENABLE_DATABASE
 		success = search_add_to_playlist(uri, playlist, nullptr,