[babl] tools: code around gcc warning about 0 length format string

[Øyvind Kolås <ok src gnome org>]

commit cfd6d8d9703fb1bb71b434b11aa74e7381a9b5b7
Author: Øyvind Kolås <pippin gimp org>
Date:   Sat May 19 13:35:04 2018 +0200

    tools: code around gcc warning about 0 length format string

 tools/babl_fish_path_fitness.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/tools/babl_fish_path_fitness.c b/tools/babl_fish_path_fitness.c
index d56ca05..cd012c0 100644
--- a/tools/babl_fish_path_fitness.c
+++ b/tools/babl_fish_path_fitness.c
@@ -91,7 +91,7 @@ static int source_no = 0;
 static int source_each (Babl *babl,
                         void *userdata)
 {
-  printf (SL);
+  printf ("%s", SL);
   babl_format_class_for_each (destination_each, babl);
 #ifdef UTF8
   printf ("──%2i %s%s", source_no++, babl->instance.name, NL);