renaming CUDA* to GPU* for some header files

test/gpu_basic.cu

diff --git a/test/cuda_basic.cu b/test/gpu_basic.cu
similarity index 100%
rename from test/cuda_basic.cu
rename to test/gpu_basic.cu

test/gpu_common.h

diff --git a/test/cuda_common.h b/test/gpu_common.h
similarity index 100%
rename from test/cuda_common.h
rename to test/gpu_common.h