Fix test cases: tensor of size 0 not supported by GPU ops yet.
Fix test cases: tensor of size 0 not supported by GPU ops yet.

Summary: TSIA

Reviewed By: bwasti

Differential Revision: D4334592

fbshipit-source-id: f101887ede2691aef8ca317e5286347c52779774

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