Removed all usages of TH_Index_Base (#17591)
Summary:
TH_Index_Base is hard coded to 0 and can be removed from the code base.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/17591
Differential Revision: D14269273
Pulled By: izdeby
fbshipit-source-id: d844e261f4af7297bad8a81e7d6dcf0a391b94e6
