[llvm] [RISCV] Add reductions to list of roots in tryToReduceVL (PR #107595)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `flang-aarch64-out-of-tree` running on `linaro-flang-aarch64-out-of-tree` while building `llvm` at step 7 "build-flang-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/53/builds/4356

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 7 (build-flang-unified-tree) failure: build (failure)
ninja: error: dependency cycle: include/flang/__fortran_builtins.mod -> include/flang/__fortran_type_info.mod -> include/flang/__fortran_builtins.mod

```

</details>

https://github.com/llvm/llvm-project/pull/107595