* logIO() and the global $xmlrpc_logging in XML-RPC.
* log_app() and the global $app_logging in APP.
* debug_fwrite(), debug_fopen(), debug_fclose(), and $debug.
see #20051.
git-svn-id: https://develop.svn.wordpress.org/trunk@19935 602fd350-edb4-49c9-b593-d223f7449a82