Add llvm-11-dev to required packages

[ericremoreynolds]

I found this was required to build on Ubuntu, otherwise cmake cannot find LLVMConfig.cmake.

Test plan

[varungandhi-src]

Is this for a specific OS version? The Docker build has been working fine and it doesn't separately install llvm-11-dev (on Ubuntu 22.04). I created a fresh VM with Ubuntu 20.04 today and I didn't require llvm-11-dev separately either.

[varungandhi-src]

Ah, looks like maybe you have a different packaging story for llvm-11. Indeed LLVMConfig.cmake is coming from llvm-11-dev as confirmed by dpkg -L llvm-11-dev, but looks like it gets installed because of llvm-11 for me.

$ aptitude why llvm-11-dev
i   llvm-11 Recommends llvm-11-dev

We should keep the docs in sync with the Dockerfile; I'll submit a PR since I can't push to your fork.

[ericremoreynolds]

I have

$ lsb_release -a 
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 20.04 LTS
Release:        20.04
Codename:       focal

I'm not an expert on this stuff, I don't know why I need to install llvm-11-dev explicitly on my machine.

I'd also be fine with just updating the docs to suggest installing it as a fix if cmake can't find LLVMConfig.cmake.

[varungandhi-src]

Thanks for the PR. This should be superseded by #82 so I'm closing this one.

[ericremoreynolds]

Awesome thanks a lot!