emacs: highlight #[foo = "bar"] attributes

Setting `OVERRIDE` to `t` overrides the conflicting highlight Emacs
places on string literals.

Fix #14347

Author: tomjakubowski

src/etc/emacs/rust-mode.el

@@ -212,9 +212,9 @@
      ;; Special types
      (,(regexp-opt rust-special-types 'words) . font-lock-type-face)
 
-     ;; Attributes like `#[bar(baz)]` or `#![bar(baz)]`
+     ;; Attributes like `#[bar(baz)]` or `#![bar(baz)]` or `#[bar = "baz"]`
      (,(rust-re-grab (concat "#\\!?\\[" rust-re-ident "[^]]*\\]"))
-      1 font-lock-preprocessor-face)
+      1 font-lock-preprocessor-face t)
 
      ;; Syntax extension invocations like `foo!`, highlight including the !
      (,(concat (rust-re-grab (concat rust-re-ident "!")) "[({[:space:][]")