[FIX] Removed std::unary_function because it can not build c++17.#2962

Merged

tqchen merged 1 commit intoapache:masterfrom higumachan:master

Apr 4, 2019

+1-1

Commits on Apr 4, 2019

Removed std::unary_function because it is deprecated and removed in newer c++(https://en.cppreference.com/w/cpp/utility/functional/unary_function )
higumachan
committed