Add Android.mk as a dependency as well

Change-Id: I19e91eb766fcc55e9a610421a67a7c8706fdaa46
diff --git a/softkeymaster/Android.mk b/softkeymaster/Android.mk
index 63c2ba1..8e19a93 100644
--- a/softkeymaster/Android.mk
+++ b/softkeymaster/Android.mk
@@ -32,4 +32,6 @@
 
 LOCAL_MODULE_TAGS := optional
 
+LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
+
 include $(BUILD_SHARED_LIBRARY)