Config.in.legacy: drop 2013.02 entries

When we release 2018.02 at the end of this cycle, those entries will
have been removed for more than five years, so we can drop them now.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>