[DAGCombiner] Don't combine (addcarry (uaddo X, Y), 0, Carry) -> (addcarry X,...

[DAGCombiner] Don't combine (addcarry (uaddo X, Y), 0, Carry) -> (addcarry X, Y, Carry) if the Carry comes from the uaddo.

Summary:
The uaddo won't be removed and the addcarry will still be
dependent on the uaddo. So we'll just increase the use count
of X and Y and potentially require a COPY.

Reviewers: spatel, RKSimon, deadalnix

Reviewed By: RKSimon

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64190

llvm-svn: 365149