[llvm] [RISCV] Add DAG combine to convert (iN reduce.add (zext (vXi1 A to vXiN)) into vcpop.m (PR #127497)

[Philip Reames via llvm-commits]

https://github.com/preames approved this pull request.

LGTM

p.s. Sorry for letting this drop, I'd thought I'd responded to this after your update, but apparently hadn't.  

https://github.com/llvm/llvm-project/pull/127497