Created by: wangkuiyi

It seems that if we make CMake functions cc_test and nv_test, defined in cmake/generic.cmake, to check the value of CMake variables WITH_GPU and WITH_TESTING, we would be able to simplify the following CMakeLists.txt snippet:

if(WITH_TESTING)
    cc_test(ddim_test SRCS ddim/ddim_test.cc DEPS ddim)
    cc_test(place_test SRCS place/place_test.cc DEPS place)

    if(WITH_GPU)
        nv_test(cuda_test SRCS cuda_test/cuda_test.cu)
        nv_test(dim_test SRCS ddim/dim_test.cu DEPS ddim)
    endif()
endif()

into

cc_test(ddim_test SRCS ddim/ddim_test.cc DEPS ddim)
cc_test(place_test SRCS place/place_test.cc DEPS place)
nv_test(cuda_test SRCS cuda_test/cuda_test.cu)
nv_test(dim_test SRCS ddim/dim_test.cu DEPS ddim)