Fix gflags build
Fix gflags build

Summary:
Our internal update of gflags in https://github.com/caffe2/caffe2/commit/b0e325ce69aeb49c28124b189be68aea83a656ef called for this change.
Closes https://github.com/caffe2/caffe2/pull/185

Differential Revision: D4657928

Pulled By: Yangqing

fbshipit-source-id: bdf9fdc63a16dafc28b690598463ec72e3c50f40

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