wget: fix redirection from HTTP to FTP server

wget: fix redirection from HTTP to FTP server

while at it, sanitize redirection in general; add printout
of every redirection hop; make sure we won't print any non-ASCII
garbage from remote server in error meesages.

function                                             old     new   delta
sanitize_string                                        -      14     +14
parse_url                                            294     301      +7
gethdr                                               190     197      +7
wget_main                                           2326    2331      +5
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 3/0 up/down: 33/0)               Total: 33 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>