Pin libnccl2 to version 2.1.2 (#2033)
Pin libnccl2 to version 2.1.2 (#2033)

* Pin libnccl2 to version 2.1.2

Version 2.1.4 exports C++ symbols that it shouldn't, which causes a
mismatch between raised exceptions and expected exceptions.

Pin this to 2.1.2 until this is solved and NVIDIA releases a new version.

* Fix for 9.1

* Actually pin 2.1.4 for 9.1

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