Additional certificates support for an apk.

Change-Id: I5b35d5728ba9d65f7ece956127270a9ca2ea0efe
diff --git a/core/definitions.mk b/core/definitions.mk
index 97a909b..8926b2b 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -1659,7 +1659,8 @@
 define sign-package
 $(hide) mv $@ $@.unsigned
 $(hide) java -jar $(SIGNAPK_JAR) \
-	$(PRIVATE_CERTIFICATE) $(PRIVATE_PRIVATE_KEY) $@.unsigned $@.signed
+    $(PRIVATE_CERTIFICATE) $(PRIVATE_PRIVATE_KEY) \
+    $(PRIVATE_ADDITIONAL_CERTIFICATES) $@.unsigned $@.signed
 $(hide) mv $@.signed $@
 endef