Texture iterators and other facilities using CUDA textures should fail to compile with NVC++

cub.test.iterator fails at runtime with NVC++. The failure occurs because of the use of texture iterators, which use CUDA textures, a feature that NVC++ does not support.

CUB texture iterator should fail to compile when using NVC++ and the tests for them should be disabled (not the entire iterator test, just the parts that use texture iterators).

```
Testing tex-ref iterator on type c
CUDA error 18 [/proj/cuda/thrust/main/dependencies/cub/cub/iterator/tex_ref_input_iterator.cuh, 111]: invalid texture reference
CUDA error 18 [/proj/cuda/thrust/main/dependencies/cub/test/test_iterator.cu, 555]: invalid texture reference
```