remove comment abput printf.   printf is now synchronous (per waveorm).
@@ -168,7 +168,4 @@ See the release notes in github. Here are some limitations.
```
- Dwarf debugging is turned off for GPUs. -g will turn on host level debugging only.
- Some simd constructs fail to vectorize on both host and GPUs.
- - There are debug versions of the runtime libraries. However, these use printf on the device
- which currently print when the kernel terminates. So it is not a very useful debug feature if the GPU
- kernel crashes.
```
