hpx5: Convert to AutotoolsPackage, several updates (#3456)
hpx5: Convert to AutotoolsPackage, several updates (#3456)

* hpx5: Convert to AutotoolsPackage, several updates

- convert to AutotoolsPackage
- add several variants
- add several dependencies
- add new version 4.0.0
- don’t set compiler flags explicitly

* hpx5: Don’t import os

* hpx5: Clean up configure arguments

* hpx5: Correct libffi configure declaration

Also add new variant “+instrumentation”.

* hpx5: Correct CUDA, MPI, OpenCL configuration

* hpx5: Use built-in libffi

Spack’s libffi installs its headers in a strange place, and hpx5 can’t pick them up.

EmreAtes/spack,lgarren/spack,LLNL/spack,skosukhin/spack,tmerrick1/spack,TheTimmy/spack,lgarren/spack,tmerrick1/spack,matthiasdiener/spack,matthiasdiener/spack,iulian787/spack,skosukhin/spack,iulian787/spack,skosukhin/spack,iulian787/spack,mfherbst/spack,LLNL/spack,krafczyk/spack,tmerrick1/spack,iulian787/spack,EmreAtes/spack,LLNL/spack,EmreAtes/spack,matthiasdiener/spack,EmreAtes/spack,TheTimmy/spack,LLNL/spack,matthiasdiener/spack,LLNL/spack,TheTimmy/spack,TheTimmy/spack,krafczyk/spack,tmerrick1/spack,mfherbst/spack,mfherbst/spack,skosukhin/spack,lgarren/spack,lgarren/spack,lgarren/spack,krafczyk/spack,mfherbst/spack,tmerrick1/spack,mfherbst/spack,krafczyk/spack,EmreAtes/spack,TheTimmy/spack,krafczyk/spack,matthiasdiener/spack,skosukhin/spack,iulian787/spack