build error in context_gpu_test.cc
build error in context_gpu_test.cc

Summary:
caffe2/caffe2/core/context_gpu_test.cc:97:31: error: implicit instantiation of undefined template 'std::__1::array<CUstream_st *, 2>' std::array<cudaStream_t, 2> temp = {0};

(fixes build issue on macOS 10.11.6)
Closes https://github.com/caffe2/caffe2/pull/296

Differential Revision: D4914191

Pulled By: Yangqing

fbshipit-source-id: 5a2c218eef0f04e0dbfcaf951dd4749424b8cfaa

davinwang/caffe2,Yangqing/caffe2,Yangqing/caffe2,bwasti/caffe2,bwasti/caffe2,davinwang/caffe2,xzturn/caffe2,sf-wind/caffe2,xzturn/caffe2,sf-wind/caffe2,xzturn/caffe2,xzturn/caffe2,Yangqing/caffe2,sf-wind/caffe2,pietern/caffe2,pietern/caffe2,davinwang/caffe2,bwasti/caffe2,pietern/caffe2,pietern/caffe2,Yangqing/caffe2,xzturn/caffe2,bwasti/caffe2,davinwang/caffe2,pietern/caffe2,davinwang/caffe2,sf-wind/caffe2,sf-wind/caffe2,bwasti/caffe2,caffe2/caffe2,Yangqing/caffe2