[gegl] gif-load: update to latest libnsgif api

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 9ce14a326300bb37446a5aabbe195179d1bec3b8
Author: Michael Drake <michael drake codethink co uk>
Date:   Sat Apr 23 22:09:14 2022 +0100

    gif-load: update to latest libnsgif api
    
    We now have to say which pixel format to decode to.
    This sets it up to match the `babl_format ("R'G'B'A u8")`.

 operations/external/gif-load.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/operations/external/gif-load.c b/operations/external/gif-load.c
index 425f8a225..9bd44ce38 100644
--- a/operations/external/gif-load.c
+++ b/operations/external/gif-load.c
@@ -133,7 +133,9 @@ prepare (GeglOperation *operation)
       g_file_get_contents (o->path, (void*)&p->gif_data, &length, NULL);
       g_assert (p->gif_data != NULL);
 
-      code = nsgif_create (&bitmap_callbacks, &p->gif);
+      code = nsgif_create (&bitmap_callbacks,
+                           NSGIF_BITMAP_FMT_R8G8B8A8,
+                           &p->gif);
       if (code != NSGIF_OK)
         g_warning ("nsgif_create: %s\n", nsgif_strerror(code));