Redefinition of CUstream with different type

[Jacobfaib]

/Users/jfaibussowit/soft/nv/legate.core.internal/arch-cu-driver/cmake_build/_deps/kvikio-src/cpp/include/kvikio/shim/cuda_h_wrapper.hpp:36:7: error: type alias redefinition with different types ('void *' vs 'struct CUstream_st *')
   36 | using CUstream    = void*;
      |       ^
/Users/jfaibussowit/soft/nv/legate.core.internal/src/cpp/legate/cuda/cuda.h:35:7: note: previous definition is here
   35 | using CUstream = struct CUstream_st*;
      |       ^

This occurs when:

1. Kvikio is built without CUDA.
2. Kvikio headers are included in a library that also shims various CUDA driver types.

IMO, Kvikio should use the right typedefs for these to match the CUDA driver API. In our case, our forward decls do need to be ABI compatible with CUDA driver, since we dlsym() the driver at runtime, but do not want to introduce a build-time dependency on the driver API.

Specifically:

#if defined(_WIN64) || defined(__LP64__)
// Don't use uint64_t, we want to match the driver headers exactly
using CUdeviceptr = unsigned long long;
#else
using CUdeviceptr = unsigned int;
#endif
static_assert(sizeof(CUdeviceptr) == sizeof(void*));

using CUresult   = int;
using CUdevice   = int;
using CUcontext  = struct CUctx_st*;
using CUstream   = struct CUstream_st*;
using CUevent    = struct CUevent_st*;
using CUfunction = struct CUfunc_st*;
using CUlibrary  = struct CUlib_st*;
using CUkernel   = struct CUkern_st*;

[madsbk]

Sounds good to me, can you submit a PR?