istream-attachment-extractor: Fixed handling attachment as the message body without MIME. Don't crash at the end after parsing the base64 data.
istream-attachment-extractor: Fixed handling attachment as the message body without MIME.
Don't crash at the end after parsing the base64 data.

dscho/dovecot,dscho/dovecot,dscho/dovecot,dscho/dovecot,dscho/dovecot