caffe2/caffe2/contrib/torch/torch_op.h: avoid shadowing warnings
caffe2/caffe2/contrib/torch/torch_op.h: avoid shadowing warnings

Summary:
Fix warnings exposed by gcc-4.9.x's -Wshadow-compatible-local
I plan to enable this for all of fbcode, soon.
See t13698406 for justification.

Rename inner "err" to "err2".

This avoids the following errors:

  caffe2/caffe2/contrib/torch/torch_op.h:263:47: error: declaration of 'err' shadows a previous local [-Werror=shadow-compatible-local]
  caffe2/caffe2/contrib/torch/torch_op.h:263:11: error: declaration of 'err' shadows a previous local [-Werror=shadow-compatible-local]

Reviewed By: Yangqing

Differential Revision: D4544812

fbshipit-source-id: b15467ba9af7ec7f391db59f706b0442cdb664c4

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