From: Michael Chang <mchang@suse.com>
Subject: export btrfs_subvol and btrfs_subvolid

We should export btrfs_subvol and btrfs_subvolid to have both visible 
to subsidiary configuration files loaded using configfile. 

Signed-off-by: Michael Chang <mchang@suse.com>

Index: grub-2.00/grub-core/fs/btrfs.c
===================================================================
--- grub-2.00.orig/grub-core/fs/btrfs.c
+++ grub-2.00/grub-core/fs/btrfs.c
@@ -2252,6 +2252,8 @@ GRUB_MOD_INIT (btrfs)
                                subvol_set_env);
   grub_register_variable_hook ("btrfs_subvolid", subvolid_get_env,
                                subvolid_set_env);
+  grub_env_export ("btrfs_subvol");
+  grub_env_export ("btrfs_subvolid");
 }
 
 GRUB_MOD_FINI (btrfs)