androidbp: Add LOCAL_MODULE_MAKEFILE

We're hardcoding LOCAL_PATH instead of using the my-dir macro.
LOCAL_MODULE_MAKEFILE is the other variable set up by this macro, used
to ensure that changes to the makefile rebuilds the objects defined in
the makefile.

Change-Id: I994b72ab9053d5a057eb3e35a8710038800432eb

androidbp/cmd/androidbp.go

@@ -346,6 +346,7 @@ func (w *androidMkWriter) handleLocalPath() error {
 	}
 
 	w.WriteString("LOCAL_PATH := " + rel + "\n")
+	w.WriteString("LOCAL_MODULE_MAKEFILE := $(lastword $(MAKEFILE_LIST))\n\n")
 	return nil
 }