Add a copy of debug policy to GSI system image

Bug: 188067818
Test: Flash RQ2A.201207.001 bramble-user with debug ramdisk & flash
  gsi_arm64-user from master, device can boot and `adb root` works
Change-Id: I37ef02628b8635e88a9e8ef917da71c8957c4be1
Merged-In: I37ef02628b8635e88a9e8ef917da71c8957c4be1
(cherry picked from commit c329a3a362bdbbc4ebe1123b1d9e835ed68a4b7d)
diff --git a/gsi_system_ext.mk b/gsi_system_ext.mk
index 45ff91f..7a43c5c 100644
--- a/gsi_system_ext.mk
+++ b/gsi_system_ext.mk
@@ -29,3 +29,7 @@
 #  telephony packages
 PRODUCT_PACKAGES += \
     CarrierConfig
+
+# Install a copy of the debug policy in GSI.
+PRODUCT_INSTALL_DEBUG_POLICY_TO_SYSTEM_EXT := true
+PRODUCT_PACKAGES += system_ext_userdebug_plat_sepolicy.cil