Fixed typo libsbitsandbytes_cpu.so

[rapsealk]

Hello bitsandbytes!

While I was investigating on some problem running bitsandbytes, I think I found a typo.

There seems nowhere using libsbitsandbytes_cpu.so(lib+s+bitsandbytes_cpu.so), but libbitsandbytes_cpu.so(lib+bitsandbytes_cpu.so) is being used.

Thanks in advance!

===================================BUG REPORT===================================
Welcome to bitsandbytes. For bug reports, please submit your error trace to: https://github.com/TimDettmers/bitsandbytes/issues
================================================================================
/usr/local/lib/python3.8/dist-packages/torch/cuda/__init__.py:82: UserWarning: CUDA initialization: Unexpected error from cudaGetDeviceCount(). Did you run some cuda functions before calling NumCudaDevices() that might have already set an error? Error 34: CUDA driver is a stub library (Triggered internally at  ../c10/cuda/CUDAFunctions.cpp:112.)
  return torch._C._cuda_getDeviceCount() > 0
CUDA SETUP: Required library version not found: libsbitsandbytes_cpu.so. Maybe you need to compile it from source?
CUDA SETUP: Defaulting to libbitsandbytes_cpu.so...
/usr/local/lib/python3.8/dist-packages/bitsandbytes/cextension.py:31: UserWarning: The installed version of bitsandbytes was compiled without GPU support. 8-bit optimizers and GPU quantization are unavailable.
  warn("The installed version of bitsandbytes was compiled without GPU support. "

[xNul]

Does this fix this bug? #156 (comment)

[rapsealk]

@xNul Sorry, but I guess it won't. Actually it substitutes libsbitsandbytes.so with libbitsandbytes.so by itself.

[xNul]

@rapsealk All good, thanks for the response

[TimDettmers]

Thanks for the PR. I need to look further into #156 and other related bugs. Thank you for your patience.