sepolicy: restrict /vendor/overlay from most coredomains

The change makes 'vendor_overlay_file' accessible only to few platform
domains like idmap, system_server, zygote and appdomain.

The overlay files contains RROs (runtime resource overlays)

Bug: 36681210
Test: Boot sailfish (treble device) from wiped flashall
Test: Connect to wifi and launch chrome to load few websites.
Test: Launch camera and record + playback video

Change-Id: I3596ca89ad51d0e7d78c75121f22ea71209ee332
Signed-off-by: Sandeep Patil <sspatil@google.com>
diff --git a/private/system_server.te b/private/system_server.te
index 4302343..90e8b10 100644
--- a/private/system_server.te
+++ b/private/system_server.te
@@ -297,6 +297,9 @@
 # Access /vendor/app
 r_dir_file(system_server, vendor_app_file)
 
+# Access /vendor/app
+r_dir_file(system_server, vendor_overlay_file)
+
 # Manage /data/app-private.
 allow system_server apk_private_data_file:dir create_dir_perms;
 allow system_server apk_private_data_file:file create_file_perms;