Fix RoIFeatureTransform Methods with ArgMax
Fix RoIFeatureTransform Methods with ArgMax

Summary:
For RoIFeatureTransform Methods with ArgMax (RoIPoolF/RoIPoolLateQuantization), the current pipeline will report
```
TypeError: I/O blob #0 of unsupported type: (BlobReference("gpu_0/roi_features"), BlobReference("gpu_0/_argmax_roi_features")) of type <type 'tuple'>
```
as in the example training: https://our.intern.facebook.com/intern/fblearner/details/51149202/

Reviewed By: viswanathgs

Differential Revision: D7907518

fbshipit-source-id: 38caa51c955f5a577d11c04688b9061cb6dd3c22

facebookresearch/Detectron,facebookresearch/Detectron,facebookresearch/Detectron