Fix segfaults when parsing very complex invalid input, like `import äˆ ð£„¯ð¢·žð±‹á”€ð””ð‘©±å®ä±¬ð©¾\n𗶽`. Co-authored-by: Guido van Rossum <guido@python.org> Co-authored-by: Pablo Galindo <pablogsal@gmail.com>