[gegl] gegl:stretch-contrast: opt out of auto-threading

[Øyvind Kolås <ok src gnome org>]

commit 118a5b27a1179fe2e91663f7d21034816ada8db2
Author: Øyvind Kolås <pippin gimp org>
Date:   Sat Aug 12 22:52:11 2017 +0200

    gegl:stretch-contrast: opt out of auto-threading

 operations/common/stretch-contrast.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/operations/common/stretch-contrast.c b/operations/common/stretch-contrast.c
index d28d7f0..0460443 100644
--- a/operations/common/stretch-contrast.c
+++ b/operations/common/stretch-contrast.c
@@ -557,6 +557,7 @@ gegl_op_class_init (GeglOpClass *klass)
 
   filter_class->process = process;
   operation_class->prepare = prepare;
+  operation_class->threaded = FALSE;
   operation_class->process = operation_process;
   operation_class->get_required_for_output = get_required_for_output;
   operation_class->get_cached_region = get_cached_region;