[php-src] PR #23814: ext/curl: fix use-after-free when setting a callback option from its own callback

Pull Request: https://github.com/php/php-src/pull/23814 Author: jvoisin php_curl_set_callable_handler() frees the previously registered callback with zend_fcc_dtor() before installing the new one. The write/read/header/progress/ etc. callbacks run with ch->in_callback set, so calling curl_setopt() with one of the callable options (CURLOPT_WRITEFUNCTION, CURLOPT_READFUNCTION, ...) from inside such a callback destroys the fcc that is still executing. For a non-closure callback such as [$obj, 'method'] whose object is only referenced by the fcc, this releases $this while its method is still on the stack, resulting in a use-after-free (closures are kept alive by the call frame, method receivers are not). Reject setting a callable option while inside a callback, matching the existing in_callback guards on curl_close() and curl_reset().