Since add_new_free_space() is exported, used outside block-group.c, rename
it to include the 'btrfs_' prefix.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>