buildroot

wget: security bump to version 1.18

Fixes:
CVE-2016-4971 - By default, on server redirects to a FTP resource, use
the original URL to get the local file name.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>