[emacs] Fix autoloading for llvm-mir-mode

[jian-lin]

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:

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

Diff of generated autoload files is as follows:

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

CC @bogner for review

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[jian-lin]

@goldsteinn @lukel97 tagging people who have touched some Emacs stuff to review this, apologies in advance if you aren't the right persons for this.

[lukel97]

LGTM, thanks!

[goldsteinn]

LGTM

[goldsteinn]

Do you need someone to merge this for you?

[jian-lin]

Do you need someone to merge this for you?

Yes. It's my first contribution to this project and I do not think I can merge things myself.

[github-actions]

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