Accept PHP 8.1's new $_FILES['full_path'] member

[gileri]

PHP 8.1 introduced a new member to the $_FILES superglobal.

This PR allows to accept both array members.

[alquerci]

@Tybaze nice catch.

Did you see it from the test suite?

I wonder if it is covered.

[Tybaze]

@alquerci , No, just reviewing the PR, got a doubt, make a custom test on an 7.4 env and trigger the error.

We should create a specific "adaptive" test for 8.1+ and before, And as it is a "Notice" I don't think it will crash the test