load ro.recovery_id property from recovery partition

Change-Id: I9dc1f325e353375d9c1c8ed949636e2404601076
diff --git a/init/util.h b/init/util.h
index 1c947ec..09d64cd 100644
--- a/init/util.h
+++ b/init/util.h
@@ -62,4 +62,5 @@
 int make_dir(const char *path, mode_t mode);
 int restorecon(const char *pathname);
 int restorecon_recursive(const char *pathname);
+std::string bytes_to_hex(const uint8_t *bytes, size_t bytes_len);
 #endif