CUDA 13 changed cuCtxCreate's signature, adding a CUctxCreateParams*
pointer as the second argument (cuCtxCreate_v4). The legacy
cuCtxCreate_v2 with the 3-argument signature is only declared under
__CUDA_API_VERSION_INTERNAL, so it can't be called from normal cgo.

Pass NULL for the new params arg, which matches the previous default
behaviour (no execution-affinity / no other extras).

The ebuild applies this patch conditionally — only when the installed
cuda.h ships CUctxCreateParams. On CUDA 12 the original source works
unchanged.

--- a/cuda/cu/context.go
+++ b/cuda/cu/context.go
@@ -12,7 +12,7 @@ type Context uintptr
 // Create a CUDA context.
 func CtxCreate(flags uint, dev Device) Context {
 	var ctx C.CUcontext
-	err := Result(C.cuCtxCreate(&ctx, C.uint(flags), C.CUdevice(dev)))
+	err := Result(C.cuCtxCreate(&ctx, nil, C.uint(flags), C.CUdevice(dev)))
 	if err != SUCCESS {
 		panic(err)
 	}