Catch cudaError_t return val (nodiscard in rocm) (#16399)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16399
Catching cudaError_t return values in a few places, because it's nodiscard in rocm. Unless we add -Wno-unused-result, it'll end up with a compilation error.
Also in c10/cuda/test, check whether a host has GPU or not. We were silently throwing out the error before (so not really testing the cuda api).
Reviewed By: bddppq
Differential Revision: D13828281
fbshipit-source-id: 587d1cc31c20b836ce9594e3c18f067d322b2934
