Increase recursion_limit in numerous crates.

This is temporarily needed for `x doc compiler` to work. They can be
removed once the `Nonterminal` is removed (#124141).

compiler/rustc_parse/src/lib.rs

@@ -4,6 +4,7 @@
 #![allow(internal_features)]
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
+#![cfg_attr(doc, recursion_limit = "256")] // FIXME(nnethercote): will be removed by #124141
 #![feature(array_windows)]
 #![feature(assert_matches)]
 #![feature(box_patterns)]