Give _VariableFunctions class a different name, so pickling works (#38033)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/38033
Pickles require class names to be actually accessible from the module
in question. _VariableFunction was not! This fixes it.
Fixes https://github.com/pytorch/pytorch/issues/37703
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Test Plan: Imported from OSS
Differential Revision: D21458068
Pulled By: ezyang
fbshipit-source-id: 2a5ac41f9d1972e300724981b9b4b84364ddc18c
