[ Bug ] GPU initialization error in backround mode
## System Information

OS: Ubuntu 18.04.1 64-bit running in an LXD container
GPU: NVIDIA GTX 960
GPU Driver: NVIDIA 410.48
CUDA: CUDA 10.0
xmrMiner: 0.3.0 (64-bit) built with GCC 7.3  using NVIDIA CUDA Toolkit 10.0

## Issue

When I start xmrMiner with the `--background` argument, the GPU fails to initialize. Without that argument, xmrMiner runs perfectly fine (on the GPU).

When running with the  `--background` argument, I get the following output:

```
>> xmrMiner --url="$URL" --user="$USER" --pass="$PASS" --background

    *** xmrMiner 0.3.0 (64 bit) for NVIDIA GPUs by psychocrypt 
    *** Built with GCC 7.3  using the Nvidia CUDA Toolkit 10.0

 psychocrypt's XMR donation address:
   43NoJVEXo21hGZ6tDG6Z3g4qimiGdJPE6GRxAmiWwm26gwr62Lqo7zRiCJFSBmbkwTGNuuES9ES5TgaVHceuYc4Y75txCTU
 for more donation addresses please read the README.md
-----------------------------------------------------------------
[2018-10-19 18:55:13] Using JSON-RPC 2.0
[2018-10-19 18:55:13] Starting Stratum on stratum+tcp://pool.supportxmr.com:5555
[2018-10-19 18:55:13] Pool set diff to 10000
[2018-10-19 18:55:13] Stratum detected new block
[2018-10-19 18:55:15] 1 miner threads started, using 'cryptonight-monero' algorithm.
[2018-10-19 18:55:15] GPU #0: GeForce GTX 960 (8 SMX), using 32 blocks of 8 threads
[2018-10-19 18:55:15] GPU 0: initialization error

GPU 0: initialization error
/home/ubuntu/xmrMinerProject/xmrMiner/cryptonight/cryptonight.cu line 179
```

Running xmrMiner without the `--background` argument passes without error:

```
>> xmrMiner --url="$URL" --user="$USER" --pass="$PASS"

    *** xmrMiner 0.3.0 (64 bit) for NVIDIA GPUs by psychocrypt 
    *** Built with GCC 7.3  using the Nvidia CUDA Toolkit 10.0

 psychocrypt's XMR donation address:
   43NoJVEXo21hGZ6tDG6Z3g4qimiGdJPE6GRxAmiWwm26gwr62Lqo7zRiCJFSBmbkwTGNuuES9ES5TgaVHceuYc4Y75txCTU
 for more donation addresses please read the README.md
-----------------------------------------------------------------
[2018-10-19 18:59:46] Using JSON-RPC 2.0
[2018-10-19 18:59:46] Starting Stratum on stratum+tcp://pool.supportxmr.com:5555
[2018-10-19 18:59:46] Pool set diff to 10000
[2018-10-19 18:59:46] Stratum detected new block
[2018-10-19 18:59:48] 1 miner threads started, using 'cryptonight-monero' algorithm.
[2018-10-19 18:59:48] GPU #0: GeForce GTX 960 (8 SMX), using 32 blocks of 8 threads
[2018-10-19 18:59:50] GPU #0: GeForce GTX 960, 235.66 H/s
[2018-10-19 19:00:00] GPU #0: GeForce GTX 960, 242.52 H/s
...
```

## Comments

I am curious to see if anyone else is facing the same issue. I suspect that this error has something to do with the new CUDA version (10.0), which might have introduced new errors. The error log does point to a specific file (/home/ubuntu/xmrMinerProject/xmrMiner/cryptonight/cryptonight.cu line 179).