[GIT-PULLS] [php-src] PR #23084: Make strtolower()/strtoupper() frameless

Pull Request: https://github.com/php/php-src/pull/23084
Author: staabm

disclaimer: this change was generated by claude opus. I have little experience with php-src development

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Both are single-argument wrappers around zend_string_tolower/upper; static analyzers and general string handling call them at very high frequency. The frameless call convention removes the call frame setup and argument copying.

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benchmark (3 runs after 2 warmup runs):

run `/Users/staabm/workspace/php-src/sapi/cli/php bin/phpstan clear-result-cache -q &&  /Users/staabm/workspace/php-src/sapi/cli/php -d memory_limit=450M bin/phpstan -v` after checking out https://github.com/phpstan/phpstan-src/pull/5942 from the git root folder.
(on first time phpstan-src checkout you need `composer install` and `make` to prepare the codebase)

before this PR:
14.39s
14.44s
14.36s

after this PR:
14.18s
14.14s
14.12s


on M4-Pro with macOS 26.6 (25G72)