Build the support Gradle repository in a SDK build

Will make it clearer for pre-submit purposes.

Change-Id: I3f1bb281e2b4163c1e3ab5f89a3b441bf5f4980b
diff --git a/Android.mk b/Android.mk
index 4abc112..8fd0693b 100644
--- a/Android.mk
+++ b/Android.mk
@@ -23,8 +23,15 @@
 .PHONY: update-support-api
 .PHONY: check-support-api
 
+.PHONY: support-gradle-archive
+support-gradle-archive: PRIVATE_LOCAL_PATH := $(LOCAL_PATH)
+support-gradle-archive:
+	$(PRIVATE_LOCAL_PATH)/gradlew -p $(PRIVATE_LOCAL_PATH) createArchive
+
 # Run the check-support-api task on a SDK build
 sdk: check-support-api
+# Run the support-gradle-archive task on a SDK build
+sdk: support-gradle-archive
 
 # Build all support libraries
 include $(call all-makefiles-under,$(LOCAL_PATH))