Provide CUBLAS with a pool-backed workspace.

[maleadt]

Fixes #365.

[codecov]

Codecov Report

Merging #443 into master will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #443      +/-   ##
==========================================
- Coverage   79.06%   79.06%   -0.01%     
==========================================
  Files         170      170              
  Lines        9275     9279       +4     
==========================================
+ Hits         7333     7336       +3     
- Misses       1942     1943       +1     

Impacted Files	Coverage Δ
lib/cublas/CUBLAS.jl	80.30% <100.00%> (+1.27%)	⬆️
lib/nvml/device.jl	81.53% <0.00%> (-1.54%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ccccc9a...457eda6. Read the comment docs.