[renderd] fixup breakage from previous commits

Bug was found and reported by Bernard Fouche, thanks!



git-svn-id: http://svn.openstreetmap.org/applications/utils/mod_tile@29405 b9d5c4c9-76e1-0310-9c85-f3177eceb1e4
[render_list] fix invalid free() in case of default mapname or tilepath



git-svn-id: http://svn.openstreetmap.org/applications/utils/mod_tile@29406 b9d5c4c9-76e1-0310-9c85-f3177eceb1e4