[php-src] Issue #7946: Rewrite zend_eval_const_expr to use a stack on the heap instead of recursion where possible?

Issue: https://github.com/php/php-src/issues/7946 Comment Author: cmb69 > If it's a matter of supporting long $x . $y chains, then we should add a concat list node. That. The concat operator is likely the only binary operator where such super-deep nesting might happen otherwise.