[llvm] [SVE ACLE] Add `NodeMap[V]` for `svcount` in SelectionDAGBuilder (PR #126089)

[Da Li 李达 via llvm-commits]

dlee992 wrote:

I think this PR doesn't need a new testcase, since #69321 has added the needed test cases.

I updated the PR description, hope it's good to go.

https://github.com/llvm/llvm-project/pull/126089