Revert "Fix for systems where int64_t == ptrdiff_t" (it was evil and didn't work anyway)
Revert "Fix for systems where int64_t == ptrdiff_t" (it was evil and didn't work anyway)

This reverts commit b7b6f8feb602fd6527c01c2e0049d7f1e195db95.

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