fix(tree-sitter): autodef treesit-available-p

This way, whether the module is enabled or not, `treesit-available-p`
will exist, even in Emacs build without treesit.

Amend: a51690f033

modules/tools/tree-sitter/autoload/compat-30.el

@@ -9,7 +9,7 @@
 
 ;; In case of Emacs builds where treesit isn't built in (to avoid void-function
 ;; errors and verbose, redundant checks everywhere).
-;;;###autoload
+;;;###autodef
 (unless (fboundp 'treesit-available-p)
   (defun treesit-available-p ()
     "Return non-nil if tree-sitter support is built-in and available."