It is common that build hosts are isolated from outside world. They
don't necessarily have wget or ftp installed.
Turn the error into warning in configure. And point FETCHER to `false'
command if neither wget nor ftp is available, so any attempt to
download will result in error.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>