sepolicy for vendor overlay

Make /(product|system/product)/vendor_overlay/<ver> have the vendor
file context.

If vendor_overlay requires to mount on the vendor directories other
than 'vendor_file', the contexts must be defined in the device
specific sepolicy files.

Bug: 119076200
Test: build and check if the files are overided and have the required
sepolicy contexts.

Change-Id: I69ed38d4ea8e7d89f56865b1ca1e26f290e9892d
diff --git a/private/file_contexts b/private/file_contexts
index fd3e1dc..13d87ff 100644
--- a/private/file_contexts
+++ b/private/file_contexts
@@ -382,6 +382,14 @@
 /(product_services|system/product_services)/overlay(/.*)?       u:object_r:vendor_overlay_file:s0
 
 #############################
+# Vendor files from /(product|system/product)/vendor_overlay
+#
+# NOTE: For additional vendor file contexts for vendor overlay files,
+# use device specific file_contexts.
+#
+/(product|system/product)/vendor_overlay/[0-9]+/.*          u:object_r:vendor_file:s0
+
+#############################
 # Data files
 #
 # NOTE: When modifying existing label rules, changes may also need to