make shape parameter op field for ReduceDimsOp
make shape parameter op field for ReduceDimsOp

Summary: Since shape tensor was allocated every time, the global allocation mutex was acquired, possibly leading to slowdown.

Reviewed By: salexspb

Differential Revision: D5263899

fbshipit-source-id: b44ff0b01342f116154ec2a9c65f91b5c0e51452

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