Cleanup omnibus-blacklist-hack rules
Cleanup omnibus-blacklist-hack rules

Summary:
Now that Buck supports a way to opt-out external C/C++ libs from omnibus linking,
this diff removes the hack we previously relied on (and which got copy-pasta-d everywhere).

Reviewed By: pixelb

Differential Revision: D5832450

fbshipit-source-id: cc3d12488f8498be6fb12bce1fedb3ad1accb518

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