Install runtime resource overlay without subdir.

Runtime resource overlay is a bare APK with just the overlaid
resources. There is no need for additional subdir.
See http://go/sku-colors.

Bug: 31692079
Change-Id: Iff3d58f941e764a7be3ec04cafeefd592bd8b944
diff --git a/core/build_rro_package.mk b/core/build_rro_package.mk
new file mode 100644
index 0000000..24cd9a3
--- /dev/null
+++ b/core/build_rro_package.mk
@@ -0,0 +1,22 @@
+#########################################################################
+## Standard rules for installing runtime resouce overlay APKs.
+##
+## Set LOCAL_RRO_SKU to the SKU name if the package should apply only to
+## a particular SKU as set by ro.boot.vendor.overlay.sku system property.
+##
+#########################################################################
+
+LOCAL_IS_RUNTIME_RESOURCE_OVERLAY := true
+
+ifneq ($(LOCAL_SRC_FILES),)
+  $(error runtime resource overlay package should not contain sources)
+endif
+
+ifeq (S(LOCAL_RRO_SKU),)
+  LOCAL_MODULE_PATH := $(TARGET_OUT_VENDOR)/overlay
+else
+  LOCAL_MODULE_PATH := $(TARGET_OUT_VENDOR)/overlay/$(LOCAL_RRO_SKU)
+endif
+
+include $(BUILD_SYSTEM)/package.mk
+