init: move selinux and seccomp set up to 2nd stage init.

If there is no valid pre-compiled SEPolicy policy, init may call
secilc, which exists on the system partition.  1st stage init won't
always live on this partition, so we need to move this SELinux setup
to 2nd stage init, which always lives on the system partition, to
ensure that both secilc and its caller are updated together.

Bug: 114059212
Test: hikey boots, sailfish boots
Change-Id: Iaf7b4af4a5c2ace16755ec2e54510ab95c53f041