Allow init to mount /odm, /vendor early

Specifically we need init to relabel (/dev/device-mapper, /dev/block/dm-?)
and other files in /dev/block/* from tmpfs to dm_device and block_device
respectively.

BUG=27805372

Change-Id: I16af6e803f8e4150481137aba24d5406872f9c62

init.te

@@ -20,6 +20,11 @@ allow init properties_serial:file { write relabelto };
 allow init property_type:file { create_file_perms relabelto };
 # /dev/socket
 allow init { device socket_device }:dir relabelto;
+# /dev/device-mapper, /dev/block(/.*)?
+allow init tmpfs:{ chr_file blk_file } relabelfrom;
+allow init tmpfs:blk_file getattr;
+allow init block_device:{ dir blk_file } relabelto;
+allow init dm_device:{ chr_file blk_file } relabelto;
 
 # setrlimit
 allow init self:capability sys_resource;