[gimp] app: fix gimp-file-save PDB procedure implementation.

[Jehan <jehanp src gnome org>]

commit 9487c5648b37414ecae3f363fce313bac2c834b6
Author: Jehan <jehan girinstud io>
Date:   Wed Oct 21 17:58:19 2020 +0200

    app: fix gimp-file-save PDB procedure implementation.
    
    The GFile was taken from the wrong argument.

 app/pdb/file-cmds.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/app/pdb/file-cmds.c b/app/pdb/file-cmds.c
index 72dbe3e278..02885bd4e4 100644
--- a/app/pdb/file-cmds.c
+++ b/app/pdb/file-cmds.c
@@ -232,7 +232,7 @@ file_save_invoker (GimpProcedure         *procedure,
   GimpProcedure       *proc;
   gint                 i;
 
-  file = g_value_get_object (gimp_value_array_index (args, 3));
+  file = g_value_get_object (gimp_value_array_index (args, 4));
 
   file_proc = gimp_plug_in_manager_file_procedure_find (gimp->plug_in_manager,
                                                         GIMP_FILE_PROCEDURE_GROUP_SAVE,