Update NNPI backend to 0.5.1.8 (#4397)
Summary:
Update of NNPI Backend to v0.5.1.8.
Pull Request resolved: https://github.com/pytorch/glow/pull/4397
Reviewed By: jfix71
Differential Revision: D20938791
Pulled By: arunm-git
fbshipit-source-id: 4f50d104db1ac274e92d9fce6fb86afd930d8511
