VR: Add sepolicy for VR HWC service

VR HWC is being split out of VR Window Manager. It creates a HW binder
interface used by SurfaceFlinger which implements the HWComposer HAL and
a regular binder interface which will be used by a system app to receive
the SurfaceFlinger output.

Bug: b/36051907
Test: Ran in permissive mode and ensured no permission errors show in
logcat.

Change-Id: If1360bc8fa339a80100124c4e89e69c64b29d2ae
diff --git a/private/system_app.te b/private/system_app.te
index 1e2245f..bab49c1 100644
--- a/private/system_app.te
+++ b/private/system_app.te
@@ -57,7 +57,7 @@
 
 allow system_app servicemanager:service_manager list;
 # TODO: scope this down? Too broad?
-allow system_app { service_manager_type -netd_service -dumpstate_service -installd_service -virtual_touchpad_service }:service_manager find;
+allow system_app { service_manager_type -netd_service -dumpstate_service -installd_service -virtual_touchpad_service -vr_hwc_service }:service_manager find;
 
 allow system_app keystore:keystore_key {
     get_state