Explain in the Thrust/CUB version mismatch diagnostic that CUB is now a part of

the CUDA toolkit.

Author: brycelelbach

thrust/system/cuda/config.h

@@ -75,6 +75,6 @@
 #include <thrust/version.h>
 #include <cub/util_namespace.cuh> // This includes <cub/version.cuh> in newer releases.
 #if THRUST_VERSION != CUB_VERSION
-#error The version of CUB in your include path is not compatible with this release of Thrust. Define THRUST_IGNORE_CUB_VERSION_CHECK to ignore this.
+#error The version of CUB in your include path is not compatible with this release of Thrust. CUB is now included in the CUDA Toolkit, so you no longer need to use your own checkout of CUB. Define THRUST_IGNORE_CUB_VERSION_CHECK to ignore this.
 #endif
 #endif