[llvm] [emacs] More consistently highlight value keywords that appear in vectors (PR #97594)

[Luke Lau via llvm-commits]

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@@ -61,6 +61,8 @@
    `(,(concat "\\<" llvm-mode-primitive-type-regexp "\\>") . font-lock-type-face)
    ;; Integer literals
    '("\\b[-]?[0-9]+\\b" . font-lock-preprocessor-face)
+   ;; Values that can appear in a vec
+   '("\\b\\(true\\|false\\|null\\|undef\\|poison\\|none\\)\\b" . font-lock-keyword-face)
----------------
lukel97 wrote:

I wonder if the `'words` paren argument to regexp-opt would also work? https://www.gnu.org/software/emacs/manual/html_node/elisp/Regexp-Functions.html#index-regexp_002dopt

```elisp
`(,(regexp-opt '("true" "false" "null" "undef" "none" "poison") 'words) . font-lock-keyword-face
```

https://github.com/llvm/llvm-project/pull/97594