Change CTS makefiles so apps are built in data not system partition.

BUG 2053298

Change-Id: I2c541c03f7c33c69cde7b0567b080710658c8d28
diff --git a/tools/cts-reference-app-lib/Android.mk b/tools/cts-reference-app-lib/Android.mk
index 471f755..8341970 100644
--- a/tools/cts-reference-app-lib/Android.mk
+++ b/tools/cts-reference-app-lib/Android.mk
@@ -19,7 +19,10 @@
 
 LOCAL_SRC_FILES := $(call all-subdir-java-files)
 
+# don't include this package in any target
 LOCAL_MODULE_TAGS := optional
+# and when built explicitly put it in the data partition
+LOCAL_MODULE_PATH := $(TARGET_OUT_DATA_APPS)
 
 LOCAL_JAVA_LIBRARIES := android.test.runner