Add SELinux filesystem relabeling to init

Since not all recoveries out there will support the OTA packages'
own labeling, check at boot if the system needs labels (and
apply them)

Change-Id: I58767977b90a78a12efe7bd9d713654eadf47e7a

author: rmcc authored 7 days ago

 Changes to be committed:
	modified:   config/common.mk
	new file:   prebuilt/common/etc/init.d/50selinuxrelabel