media_tree: don't use any timeout when preparsing

You don't want to timeout when you request user credentials. Preparse should
only be canceled only by the user.

src/media_source/media_tree.c

@@ -331,6 +331,6 @@ vlc_media_tree_Preparse(vlc_media_tree_t *tree, libvlc_int_t *libvlc,
     media->i_preparse_depth = 1;
     vlc_MetadataRequest(libvlc, media, META_REQUEST_OPTION_SCOPE_ANY |
                         META_REQUEST_OPTION_DO_INTERACT,
-                        &input_preparser_callbacks, tree, -1, NULL);
+                        &input_preparser_callbacks, tree, 0, NULL);
 #endif
 }