"AES Authenticated Encryption example" is wrong and insecure

[hendi]

From manual page: https://php.net/function.openssl-encrypt

The example "Example #2 AES Authenticated Encryption example prior to PHP 7.1" is wrong and insecure, in the way that the hmac doesn't consider the IV. That means that it's possible take an encrypted and authenticated value, change its IV (the first bytes) and still pass the hmac check.