[llvm] [GlobalISel] Fix [SU]SUBO combine (PR #116998)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

The adde combine also writes a 1 into the carry-out:
https://github.com/llvm/llvm-project/blob/dbe159b3f74ea41e16782fe5708756507d4a014f/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp#L7398

https://github.com/llvm/llvm-project/pull/116998