Can't build libafl_qemu in Dockerfile

[vringar]

Issue confirmed on 8c773a6

Describe the bug
When trying to build libafl_qemu in the docker container, the build errors because it can't find libafl_qemu/build_linux.rs.
As I'm trying to use the container as a build environment because my distribution doesn't ship and up-to-date version of LLVM, this is unfortunate.
Should I just modify the Dockerfile for my usecase or is this something I should try and upstream?

To Reproduce
Steps to reproduce the behavior:

1. docker build -t libafl .
2. docker run --name libafl --rm -it libafl
3. (In the Docker shell) cargo build -p libafl_qemu

Expected behavior

I would expect the build to complete successfully.