Fix missing libraries when library versioning is enabled. (#2617)
Fix missing libraries when library versioning is enabled. (#2617)

* Copy and install all mkldnn libraries if versioning is enabled on linux.

* Replace magic numbers with variables.

* Support mkl-dnn library versioning on macos.

NervanaSystems/ngraph,NervanaSystems/ngraph,NervanaSystems/ngraph,NervanaSystems/ngraph