ril: Add guard makefile

Change-Id: Id90f22a1af3187e312ff1d860799f8c0fcef61fd
diff --git a/Android.mk b/Android.mk
new file mode 100644
index 0000000..5e2c589
--- /dev/null
+++ b/Android.mk
@@ -0,0 +1,5 @@
+RIL_PATH := $(call my-dir)
+
+ifeq ($(RIL_PATH),$(call project-path-for,ril))
+include $(call first-makefiles-under,$(RIL_PATH))
+endif