Trigger qcom-post-boot from dev.bootcomplete

Occasionally init.svc.bootanim hangs in the "stopping" state, which means
qcom-post-boot never starts.  Since qcom-post-boot is a critical service,
trigger it from dev.bootcomplete instead.

Change-Id: Id06e66999da35fde51ae5d95c721c18487c11a9e