bug#60054: 29.0.60; Infinite loop when there are cyclic path in the parse tree

[Eli Zaretskii <eliz@gnu.org>]

> From: Yuan Fu <casouri@gmail.com>
> Date: Sat, 17 Dec 2022 15:28:01 -0800
> Cc: 60054@debbugs.gnu.org
> 
> > In this particular case, it is the siblings’ parent that equals to the
> > node. Ie, node->sibling->parent = node.  If your intention is to protect
> > us from this particular case, switching to use cursors will avoid this
> > bug.
> 
> Ok, I made the change to use cursor API with tests. Hopefully this is
> the last time we need to change treesit.c before release.

This broke the Windows build (I fixed it).  You cannot start using new
tree-sitter functions without adding the boilerplate code for loading
them dynamically from the shared library at run time.

> The node->sibling->parent = node cyclic path should be fixed by this
> change, do you still want checks for it?

If that problem can never happen, there's no need for the checks.

Thanks.