[gegl] workshop: include config.h for unpremul.c

[Øyvind Kolås <ok src gnome org>]

commit 0029fb9708f1ed9a0154d3ef7622e64161f05697
Author: Øyvind Kolås <pippin gimp org>
Date:   Tue Mar 29 21:53:17 2016 +0200

    workshop: include config.h for unpremul.c

 operations/workshop/unpremul.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/operations/workshop/unpremul.c b/operations/workshop/unpremul.c
index 6fb7b8e..3a9e950 100644
--- a/operations/workshop/unpremul.c
+++ b/operations/workshop/unpremul.c
@@ -16,6 +16,8 @@
  * Copyright 2006 Øyvind Kolås <pippin gimp org>
  */
 
+#include "config.h"
+
 #ifdef GEGL_PROPERTIES
 
    /* no properties */