userspace: bytetest: add a new line after error message

Signed-off-by: Du Huanpeng <u74147@gmail.com>
diff --git a/userspace/bytetest.c b/userspace/bytetest.c
index aa48b9b..0200d2e 100644
--- a/userspace/bytetest.c
+++ b/userspace/bytetest.c
@@ -25,7 +25,7 @@
 	size_t uncomp_size;
 
 	if (argc != 2) {
-		fputs("Give uncompressed size as the argument", stderr);
+		fputs("Give uncompressed size as the argument\n", stderr);
 		return 1;
 	}