Vectorization Compilation Problem on x86-Cuda Builds

[rchen20]

Marbl is having an issue building with -DRAJA_ENABLE_VECTORIZATION=On on x86-Cuda with clang, using RAJA v2022.10.5. Reported by William Hawkins.

The following clang+nvcc flags fail to build:
-march=core-avx2
-march=native

With this error:
error: "RAJA::expt::Register<int64_t, RAJA::expt::avx_register> (const RAJA::expt::Register<int64_t, RAJA::expt::avx_register> &) const" contains a vector, which is not supported in device code

Clang does not recognize -march=avx2.

Note: This is being tried on RZWHIPPET, but should investigate whether clang+nvcc is working anyway (probably on Pascal).