Description

If the user sets-up MKL using Intel provided setup scripts prior to building ArrayFire, all environment variables are taken care of by the Intel setup scripts. This change addresses the scenario where oneAPI basetoolkit is installed but the setup script is not run before building ArrayFire.

With this additional environment variable based lookup, in the case MKL setup script is not run, ArrayFire CMake tries to locate MKL based on ONEAPI installation root. This change essentially enables easier look up of MKL installation for building ArrayFire using oneMKL. However, note that to run the built tests/examples the user needs to make sure oneMKL libraries are available via PATH or LD_LIBRARY_PATH for runtime programs to find them.

Changes to Users

None to library users. An minor ease of use enabler for ArrayFire developers.

Checklist

Rebased on latest master
Code compiles
~~[ ] Tests pass~~
~~[ ] Functions added to unified API~~
~~[ ] Functions documented~~