[php-src] PR #25244: Fix overflow in optimizer block-pass complexity guard

Pull Request: https://github.com/php/php-src/pull/25244 Author: joshtrichards The block-pass complexity guard multiplies the basic-block count by the variable count using 32-bit unsigned arithmetic. For sufficiently large functions, the product can wrap below the 64M threshold and bypass the guard. The guard was introduced for [Bug #74250](https://bugs.php.net/bug.php?id=74250) via commit 7ea2616 to skip expensive block-pass optimization of large functions. Overflow can defeat that safeguard and potentially cause excessive compilation latency. Changes: - Widen the variable-count addition to uint64_t and compare against the threshold divided by the block count. This avoids addition and multiplication overflow while preserving the exact threshold and zero-block behavior. The division uses 32-bit operands on both 32-bit and 64-bit targets.