Add the selinux policy version number.

Bug: 8841348
Change-Id: I1acf355b8e700500eeb0ddcbb8203a4769bde3bc
diff --git a/sepolicy.version b/sepolicy.version
new file mode 100644
index 0000000..45a4fb7
--- /dev/null
+++ b/sepolicy.version
@@ -0,0 +1 @@
+8