linphone: Hard-enable IPv6 support

Signed-off-by: Quentin Glidic <sardemff7+git@sardemff7.net>
linphone: Fix DOWNLOADS

Signed-off-by: Quentin Glidic <sardemff7+git@sardemff7.net>
linphone: Bump to 3.6.1

Signed-off-by: Quentin Glidic <sardemff7+git@sardemff7.net>