package/ytree: uses fork(), needs MMU
Fixes [1]:
login.c:(.text+0x546): undefined reference to `fork'
[1] http://autobuild.buildroot.net/results/bcbd0b826d5af1d429c23255d63dce6c7080085e
Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>