[php-src] PR #23304: Defer SAVE_OPLINE() on the INSTANCEOF fast path

Pull Request: https://github.com/php/php-src/pull/23304 Author: staabm disclaimer: this change was generated by claude opus. I have little experience with php-src development ---- The object paths (inline cache and instanceof walk) run no user code and cannot throw; only releasing a TMP operand (destructor), fetching a late-bound class (op2 UNUSED) and the undefined-variable warning need the opline saved, and now save it explicitly. ---- after PR ``` ➜ php-src git:(defer-save-opline) ✗ sapi/cli/php -n -d opcache.enable_cli=0 instanceof_fast_path_repro.php PHP 8.6.0-dev iterations=30000000 rounds=7 case best(s) avg(s) sink ---------------------------------------------------- baseline 0.101673 0.102430 0 class-hit 0.139364 0.140235 0 interface-hit 0.146674 0.148583 0 instanceof / baseline ratios (best time, lower is better): class-hit 1.3707x interface-hit 1.4426x ``` before PR ``` ➜ php-src git:(defer-save-opline) ✗ sapi/cli/php_old -n -d opcache.enable_cli=0 instanceof_fast_path_repro.php PHP 8.6.0-dev iterations=30000000 rounds=7 case best(s) avg(s) sink ---------------------------------------------------- baseline 0.101893 0.102754 0 class-hit 0.134350 0.135289 0 interface-hit 0.143015 0.144332 0 instanceof / baseline ratios (best time, lower is better): class-hit 1.3185x interface-hit 1.4036x ``` using [instanceof_fast_path_repro.php](https://gist.github.com/staabm/7154c8b38df6c740f5f9ab58052b0fec)