The ftp server at ftp.gnu.org is likely to be retired at some point soon
so siwtch over to the http/https services.
This means bitbake-selftest doesn't have ftp test urls, however finding stable
ftp test servers is proving increasingly hard.
(Bitbake rev: 892a08245ddb21a464aeb37d3e32377e99dd7e2b)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>