Problem is that page 0 and its possible enrryption information
is not read for undo tablespaces.

fil_crypt_get_latest_key_version(): Do not send event to
encryption threads if event does not yet exists. Seen
on regression testing.

fil_read_first_page: Add new parameter does page belong to
undo tablespace and if it does, we do not read FSP_HEADER.

srv_undo_tablespace_open : Read first page of the tablespace
to get crypt_data if it exists and pass it to fil_space_create.

Tested using innodb_encryption with combinations with
innodb-undo-tablespaces.