Due to `maledong_private@qq.com` is useless because I cannot log
in with the email address (GitHub doesn't support `qq` mail well),
and I've successfully changed my email account to
`maledong_github@outlook.com` instead.
So I removed my old useless email address and keep the new
one for the same account 'MaleDong', because there're two
'MaleDong' Accounts and they are both pointing to me.

The final solution is that to add my own email account address
into the '.mailmap' to let AUTHORS re-generated.

remove useless email account in `AUTHOR` so as to keep the file in union with `.mailmap`