iolog: fix link without zlib

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/iolog.c b/iolog.c
index 19e96d2..3b39f4c 100644
--- a/iolog.c
+++ b/iolog.c
@@ -900,6 +900,12 @@
 	return 0;
 }
 
+int iolog_file_inflate(const char *file)
+{
+	log_err("fio: log inflation not possible without zlib\n");
+	return 1;
+}
+
 #endif
 
 void flush_log(struct io_log *log)