core/busybox: let's re-add /etc/inittab support While busybox has weird /etc/inittab support the predefined actions without it are too minimalistic so re-add the support for it but don't install an /etc/inittab file. The file /etc/inittab file is still installed with sysvinit but if someone wants to use busybox's init it should create its own /etc/inittab file with the busybox syntax and do not install sysvinit afterwards.