[llvm] SLP/RISCV: add test for vectorized ctpop, like in X86 (PR #65330)

[Yueh-Ting Chen via llvm-commits]

eopXD wrote:

Why specifically `ctpop`. There are much more coverage for the X86 backend, is the whole plan to add them commit by commit to the RISC-V backend?

https://github.com/llvm/llvm-project/pull/65330