Fix PHP session file overload (#2793)

toolset/setup/linux/languages/php/php.ini

@@ -1400,7 +1400,7 @@ session.save_handler = files
 ; where MODE is the octal representation of the mode. Note that this
 ; does not overwrite the process's umask.
 ; http://php.net/session.save-path
-;session.save_path = "/tmp"
+session.save_path = "3;/tmp"
 
 ; Whether to use cookies.
 ; http://php.net/session.use-cookies