[gegl] ff-save: add compatibility for slightly vintage ffmpeg

[Øyvind Kolås <ok src gnome org>]

commit 69ede9389a6e9cef84b6ebcdedff5b32cc3fb72f
Author: Øyvind Kolås <pippin gimp org>
Date:   Fri Jan 8 19:28:45 2016 +0000

    ff-save: add compatibility for slightly vintage ffmpeg

 operations/external/ff-save.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/operations/external/ff-save.c b/operations/external/ff-save.c
index 03e49a2..3376531 100644
--- a/operations/external/ff-save.c
+++ b/operations/external/ff-save.c
@@ -87,6 +87,10 @@ property_int (me_subpel_quality, _("me-subpel-quality"), 0)
 #include <libavutil/opt.h>
 #include <libswscale/swscale.h>
 
+#ifndef AV_CODEC_CAP_VARIABLE_FRAME_SIZE
+#define AV_CODEC_CAP_VARIABLE_FRAME_SIZE  CODEC_CAP_VARIABLE_FARME_SIZE
+#endif
+
 typedef struct
 {
   gdouble    frame;