Write out export_includes whenever the module is built.

Bug: 6362268
Change-Id: If872cf8fe597a02e6ca740a181cea85f486df98e
diff --git a/core/binary.mk b/core/binary.mk
index 5cb17bc..70af9b9 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -702,3 +702,6 @@
 else
 	$(hide) touch $@
 endif
+
+# Make sure export_includes gets generated when you are running mm/mmm
+$(LOCAL_BUILT_MODULE) : | $(export_includes)