[cua] Fix cuda.h path for downloaded CUDA dependencies (#9604)
[cua] Fix cuda.h path for downloaded CUDA dependencies (#9604)

Like `libdevice.10.bc` previously, `cuda.h` was also copied to
a nested directory `cuda.h/cuda.h`. This is because CMake
`file (COPY)` expects a destination directory. Now give
`file (COPY)` a proper destination directory to avoid nesting
directories to fix missing `cuda.h` header issue.
iree-org/iree,google/iree,iree-org/iree,google/iree,google/iree,iree-org/iree,google/iree,google/iree,iree-org/iree,iree-org/iree,iree-org/iree,google/iree,google/iree,iree-org/iree