[llvm] [emacs] Fix autoloading for llvm-mir-mode (PR #98984)

[Lin Jian via llvm-commits]

https://github.com/jian-lin created https://github.com/llvm/llvm-project/pull/98984

Without this patch, the autoloading of the major mode `llvm-mir-mode` is not generated, which breaks its autoloading functionality.

To test this patch, use the following command to generate an autoload file:

```console
cd llvm/utils/emacs
emacs --quick --batch --load=package --eval='(package-generate-autoloads "llvm-mir-mode" ".")'
```

Diff of generated autoload files is as follows:

```diff
> (autoload 'llvm-mir-mode "llvm-mir-mode" "\
> A major mode for editing LLVM MIR files.
> 
> (fn)" t)
```

CC @bogner for review

>From 5929ff0ed807fd4773411cff0fb66f5b01cd72e6 Mon Sep 17 00:00:00 2001
From: Lin Jian <me at linj.tech>
Date: Tue, 16 Jul 2024 10:28:50 +0800
Subject: [PATCH] [emacs] Fix autoloading for llvm-mir-mode

---
 llvm/utils/emacs/llvm-mir-mode.el | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/utils/emacs/llvm-mir-mode.el b/llvm/utils/emacs/llvm-mir-mode.el
index 5ded9cce50bb7..e53ffe825478b 100644
--- a/llvm/utils/emacs/llvm-mir-mode.el
+++ b/llvm/utils/emacs/llvm-mir-mode.el
@@ -56,7 +56,7 @@
    llvm-font-lock-keywords)
   "Keyword highlighting specification for `llvm-mir-mode'.")
 
- ;;;###autoload
+;;;###autoload
 (define-derived-mode llvm-mir-mode prog-mode "LLVM MIR"
   "A major mode for editing LLVM MIR files."
   (setq-local comment-start "; ")