init: Move prototypes for util.c into util.h

Change-Id: I46a91849ce5297eb2597dd6134412f817564ec24
diff --git a/init/builtins.c b/init/builtins.c
index 8e5eed8..7696954 100644
--- a/init/builtins.c
+++ b/init/builtins.c
@@ -36,6 +36,7 @@
 #include "property_service.h"
 #include "devices.h"
 #include "parser.h"
+#include "util.h"
 
 #include <private/android_filesystem_config.h>