Make workspace id type consistent with net-rewriting pipeline
Make workspace id type consistent with net-rewriting pipeline

Summary: There are two components that deal with workspace ids: 1) comm framework, 2) injection of GLOBAL_WORKSPACE_ID. The type of workspace id should be consistent for these components. 32 bits integers should be sufficient for such ids.

Reviewed By: akyrola

Differential Revision: D6443675

fbshipit-source-id: 7b0e8a3b005683350706fa5c330abf0a9d4881dd

xzturn/caffe2,Yangqing/caffe2,Yangqing/caffe2,caffe2/caffe2,davinwang/caffe2,xzturn/caffe2,davinwang/caffe2,xzturn/caffe2,Yangqing/caffe2,davinwang/caffe2,xzturn/caffe2,Yangqing/caffe2,davinwang/caffe2,Yangqing/caffe2,xzturn/caffe2,davinwang/caffe2