[php-src] PR #24559: Fix GH-24552: Case-insensitive substr_compare(), ksort() and krsort() are locale-dependent

Pull Request: https://github.com/php/php-src/pull/24559 Author: sirreal Fixes GH-24552. Case-insensitive substr_compare() and ksort()/krsort() with SORT_FLAG_CASE now use ASCII case conversion, as the [strtolower-ascii RFC](https://wiki.php.net/rfc/strtolower-ascii) and the PHP 8.2 UPGRADING notes say they do. They called zend_binary_strncasecmp_l() and zend_binary_strcasecmp_l(), which use the C library's tolower() and follow LC_CTYPE. #7506 switched string_case_compare_function() to ASCII, which changed sort(), but not these two callers. ```php setlocale(LC_CTYPE, 'tr_TR.UTF-8'); // glibc var_dump(substr_compare('I', 'i', 0, 1, true)); // before: int(-32), after: int(0) $keys = ['I' => 0, 'h' => 0]; ksort($keys, SORT_STRING | SORT_FLAG_CASE); echo implode(',', array_keys($keys)); // before: I,h, after: h,I, as sort() orders values ``` This changes results under a non-C LC_CTYPE in a patch release. It targets PHP-8.4 because 8.2's UPGRADING already documents the ASCII behavior; I can retarget it to master instead. Each test needs a tr_TR.UTF-8 locale and skips without one. The CI workflows generate no locales, so the tests probably skip in CI. On a PHP-8.4 debug build on Debian trixie (glibc 2.41), each test fails without its fix and passes with it, and ext/standard/tests/array and ext/standard/tests/strings pass. zend_binary_strcasecmp_l() and zend_binary_strncasecmp_l() now have no callers in php-src. They stay because they are ZEND_API on a stable branch.