We did not allocate a cache slot for FETCH_CLASS. This is already
fixed on newer PHP versions.

For the sake of simplicity I'm using a separate hashtable, rather
than trying to do hash perturabation on the double strings.

Forgot the git add again...

At least on Windows, the temporary directory may contain tilde signs,
which would result in an INI parse error.

For now, don't treat FE_FETCH op2 as no-val use. See GH-4982.

* PHP-7.2:
  Fix $x = (bool)$x; for undefined with opcache

And `$x = !$x`

Noticed while working on GH-4912

The included test would not emit undefined variable errors in php 8.0
with opcache enabled. The command used:

```
php -d zend_extension=opcache.so --no-php-ini -d error_reporting=E_ALL \
    -d opcache.file_cache= -d opcache.enable_cli=1  test.php
```

* PHP-7.2:
  Fixed bug #78747