put extra recovery keys in the product definition

Change-Id: I71637cd578b24891c10171aa59406848649be703
diff --git a/core/product_config.mk b/core/product_config.mk
index 433fae2..4f4f97d 100644
--- a/core/product_config.mk
+++ b/core/product_config.mk
@@ -303,6 +303,10 @@
 PRODUCT_OTA_PUBLIC_KEYS := $(sort \
     $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_OTA_PUBLIC_KEYS))
 
+PRODUCT_EXTRA_RECOVERY_KEYS := $(sort \
+    $(PRODUCTS.$(INTERNAL_PRODUCT).PRODUCT_EXTRA_RECOVERY_KEYS))
+
+
 # ---------------------------------------------------------------
 # Simulator overrides
 ifeq ($(TARGET_PRODUCT),sim)