- fix one memleak if get_filename failed

- cleanup according to Joerg's feedback:

"url_for_string: If fetchParseURL returned successful, you should always
have a scheme set. The logic for anonftp should only be needed for very
broken server -- do you know of any such?

download_internal:
Specifying 'p' is now a nop -- it is tried by default first with
fall-back to active FTP."

Signed-off-by: Xavier Chantry <shiningxc@gmail.com>
[Dan: remove from pacman.conf and pacman.conf.5]
Signed-off-by: Dan McGee <dan@archlinux.org>