[llvm] [vim] Fix command already exists on opening multiple mir buffers (PR #82410)

[Fraser Cormack via llvm-commits]

frasercrmck wrote:

Thanks for the PR! Sorry for the delay.

It took me a bit of fiddling to reproduce the error. I had only the `llvm.vim` and `tablegen.vim` files copied to my local `nvim` config, and I didn't see any issue. When I copied over the `mir.vim` files I started seeing the issue you report. It does seem like plain `vim` also shows the same problem.

I noticed I wasn't seeing the same issue when opening a tablegen file, so I poked around for a bit. I think the problem with MIR is because it doesn't have `delcommand HiLink`. If I add that command to `mir.vim`, the problem also goes away. What do you think about that fix instead?

https://github.com/llvm/llvm-project/pull/82410