Unify boxed function signature between jit and c10 (#37034)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/37034
c10 takes a Stack* in boxed functions while JIT took Stack&.
c10 doesn't return anything while JIT returns an int which is always zero.
This changes JIT to follow the c10 behavior.
ghstack-source-id: 106834069
Test Plan: unit tests
Differential Revision: D20567950
fbshipit-source-id: 1a7aea291023afc52ae706957e9a5ca576fbb53b
