Throw a ValueError when the parameter includes NUL bytes in putenv and getenv

[LamentXU123]

Currently string in putenv and getenv can be truncated by NUL:

<?php
var_dump(putenv("PHP_PUTENV_NUL_TEST=va\0ue"));
echo getenv('PHP_PUTENV_NUL_TEST');
echo getenv("PHP_PUTENV_NUL_TEST\0asd");

output:

bool(true)
vava

Reproduce in https://3v4l.org/ngSWJ
According to the newest policy these cases are supposed to resulted in a ValueError.

[devnexen]

nit: I think getenv()/putenv() entries can be crammed into one wdyt ?