Inline some hot lint pass functions.

These each have a single call site, due to being called from a
"combined" lint pass.

compiler/rustc_lint/src/hidden_unicode_codepoints.rs

@@ -121,6 +121,7 @@ impl EarlyLintPass for HiddenUnicodeCodepoints {
         }
     }
 
+    #[inline]
     fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
         // byte strings are already handled well enough by `EscapeError::NonAsciiCharInByteString`
         match &expr.kind {