Keep full compatibility between CUDA v5 and v6

Author: giordano

ext/ReactantCUDAExt.jl

@@ -12,7 +12,13 @@ using Reactant.Ops: @opcall
 
 using Enzyme
 using Adapt: Adapt, adapt
-using CUDA: CUDA, CuDim, DenseCuArray, unsafe_cached_load, CUDACore
+using CUDA: CUDA, CuDim, DenseCuArray, unsafe_cached_load
+# Compatibility for CUDA v5 and v6
+if isdefined(CUDA, :CUDACore)
+    using CUDA: CUDACore
+else
+    const CUDACore = CUDA
+end
 
 using GPUCompiler: GPUCompiler
 using GPUArraysCore: @allowscalar