wget: fix static link with gnutls

When statically linking with gnutls, we get definition clash error for
base64_encode which is also defined by gnutls.

This commit adds patch to rename base64_{encode,decode} defined in wget.

Signed-off-by: Rahul Bedarkar <rahul.bedarkar@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>