https://wiki.php.net/rfc/strtolower-ascii means that these functions no longer
depend on the current locale in php 8.2. Before that, this was unsafe to
evaluate at compile time.
Followup to GH-7506
Add strcmp/strcasecmp/strtolower/strtoupper functions
Add bin2hex/hex2bin and related functions
Update test of garbage collection using strtolower to use something else to create a refcounted string