system: sysvinit needs MMU
It uses spawn() and thus fork(), so it needs an MMU.
Fixes a build issue reported on IRC for a cortex-m4 build:
http://pastebin.com/dGCsy0sr
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>