bug#59459: 29.0.50; Compilation warnings without tree-sitter

[Yuan Fu]

[Continuing from bug#59426]

Those warnings are due to no-tree-sitter build not having functions
defined in treesit.c. Eli fixed those warnings by adding
declare-function’s in every file using those functions. Can we make it a
bit nicer for lisp developers? Maybe defining those functions with
dummies with something like

(defun xxx
(error ’treesit "Tree-sitter not available"))

?

Yuan