Android.bp: set sepolicy version for use by init

Init needs to be aware of the policy version defined in sepolicy
for on-device compilation.

Bug: 124499219
Test: build and boot a device. Try both precompiled and on-device
compiled policy.

Change-Id: Iba861aeb4566405aedcbe3c2bad48e1e50126370
diff --git a/Android.mk b/Android.mk
index bb6cb53..ab88003 100644
--- a/Android.mk
+++ b/Android.mk
@@ -1,12 +1,9 @@
 LOCAL_PATH:= $(call my-dir)
 
 include $(LOCAL_PATH)/definitions.mk
+include $(LOCAL_PATH)/policy_version.mk
 
 include $(CLEAR_VARS)
-# SELinux policy version.
-# Must be <= /sys/fs/selinux/policyvers reported by the Android kernel.
-# Must be within the compatibility range reported by checkpolicy -V.
-POLICYVERS ?= 30
 
 MLS_SENS=1
 MLS_CATS=1024