[gimp] app: add a reason string for internal zlib compression in GIMP 2.10.

[Jehan <jehanp src gnome org>]

commit 0fa2ef9118c41d6862077cd3a0a15541182e7a95
Author: Jehan <jehan girinstud io>
Date:   Mon Sep 10 18:53:50 2018 +0200

    app: add a reason string for internal zlib compression in GIMP 2.10.
    
    Even though chosen as a parameter to gimp_image_get_xcf_version() and
    not a feature within the image itself, we also want to list this reason
    in the compatibility list.

 app/core/gimpimage.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/app/core/gimpimage.c b/app/core/gimpimage.c
index 9d86b81be0..23dae7bb41 100644
--- a/app/core/gimpimage.c
+++ b/app/core/gimpimage.c
@@ -2527,7 +2527,11 @@ gimp_image_get_xcf_version (GimpImage    *image,
 
   /* need version 8 for zlib compression */
   if (zlib_compression)
-    version = MAX (8, version);
+    {
+      ADD_REASON (g_strdup_printf (_("Internal zlib compression was "
+                                     "added in %s"), "GIMP 2.10"));
+      version = MAX (8, version);
+    }
 
   /* if version is 10 (lots of new layer modes), go to version 11 with
    * 64 bit offsets right away