util-lib: split out IO related calls to io-util.[ch]
diff --git a/src/tmpfiles/tmpfiles.c b/src/tmpfiles/tmpfiles.c
index e574e5a..457d721 100644
--- a/src/tmpfiles/tmpfiles.c
+++ b/src/tmpfiles/tmpfiles.c
@@ -46,6 +46,7 @@
 #include "escape.h"
 #include "fd-util.h"
 #include "formats-util.h"
+#include "io-util.h"
 #include "label.h"
 #include "log.h"
 #include "macro.h"