message: Fix bug where cmake overwrites cuda flags on CUDA8
diff: @@ -20,9 +20,6 @@ if(BUILD_GPU)
  project(Ginkgo LANGUAGES CXX CUDA)
  set(CMAKE_CUDA_STANDARD_REQUIRED true)
  set(CMAKE_CUDA_STANDARD 11)
  - if(CMAKE_CUDA_COMPILER_VERSION VERSION_LESS 9)
  - set(CMAKE_CUDA_FLAGS "--expt-relaxed-constexpr")
  - endif()
  if(SET_CUDA_HOST_COMPILER)
  set(CMAKE_CUDA_FLAGS
  "--compiler-bindir ${CMAKE_CXX_COMPILER} ${CMAKE_CUDA_FLAGS}")
  