Note it worked on my computer with beignet installed (intel GPU) but on a VM, I got this message so I guess it won't work for most users:

hashcat (v4.0.0) starting...

Cannot find an OpenCL ICD loader library.

You are probably missing the native OpenCL runtime or driver for your platform.

* AMD GPUs on Linux require this runtime and/or driver:
  "RadeonOpenCompute (ROCm)" Software Platform (1.6.180 or later)
* Intel CPUs require this runtime and/or driver:
  "OpenCL Runtime for Intel Core and Intel Xeon Processors" (16.1.1 or later)
* Intel GPUs on Linux require this runtime and/or driver:
  "OpenCL 2.0 GPU Driver Package for Linux" (2.0 or later)
* NVIDIA GPUs require this runtime and/or driver:
  "NVIDIA Driver" (367.x or later)

It might also be because I used beignet-devel as builddep because this application requires CL\cl.h which I did not find anywhere else. Other disto usually have a package that contains the Khronos opencl headers. Any advise on this is welcome.

I can't imagine it works in a VM as there's no hardware graphics to load one of the drivers. Will have to investigate including the khronos headers (much like vulkan) as they will conflict with beignet-devel which already includes a version of them.