"unspecified launch" failure on NVidia TX1
I can sucessfully run `./xmrMiner --benchmark` once per reboot. After a Ctrl+C, I am unable to restart the benchmark or regular mining. On first run, if I don't add `--benchmark`, it also fails to start, always with the same error, as below:

```
    *** xmrMiner 0.2.1 (64 bit) for NVIDIA GPUs by psychocrypt
    *** Built with GCC 5.4  using the Nvidia CUDA Toolkit 8.0

 psychocrypt's XMR donation address:
   43NoJVEXo21hGZ6tDG6Z3g4qimiGdJPE6GRxAmiWwm26gwr62Lqo7zRiCJFSBmbkwTGNuuES9ES5TgaVHceuYc4Y75txCTU
 for more donation addresses please read the README.md
-----------------------------------------------------------------
[2017-08-31 05:10:58] Using JSON-RPC 2.0
[2017-08-31 05:10:58] Starting Stratum on stratum+tcp://pool.usxmrpool.com:5555
[2017-08-31 05:10:58] Pool set diff to 8000.01
[2017-08-31 05:10:58] Stratum detected new block
[2017-08-31 05:11:00] 1 miner threads started, using 'cryptonight' algorithm.
[2017-08-31 05:11:00] GPU #0: NVIDIA Tegra X1 (2 SMX), using 8 blocks of 8 threads

GPU 0: unspecified launch failure
/home/ubuntu/src/xmrMiner/cryptonight/cuda_cryptonight_extra.cu line 231
```

Here is my commandline:

`./xmrMiner --launch 8x8 -o stratum+tcp://pool.usxmrpool.com:5555 -u <key> -p x`