post process the system properties

Change-Id: Ib78fe238d90dd4523326e4fa088d9333edc9e299
diff --git a/core/Makefile b/core/Makefile
index 0af846e..5d4a283 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -51,6 +51,7 @@
 	        echo "#" >> $@;
 	$(hide) $(foreach line,$(ADDITIONAL_DEFAULT_PROPERTIES), \
 		echo "$(line)" >> $@;)
+	build/tools/post_process_props.py $@
 
 # -----------------------------------------------------------------
 # build.prop
@@ -161,6 +162,7 @@
 		        echo "#" >> $@; )
 	$(hide) $(foreach line,$(ADDITIONAL_BUILD_PROPERTIES), \
 		echo "$(line)" >> $@;)
+	$(hide) build/tools/post_process_props.py $@
 
 build_desc :=