[llvm] Re-apply (#89047):[Exegesis][RISCV] Add RISCV support for llvm-exegesis (PR #120419)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `bolt-x86_64-ubuntu-clang` running on `bolt-worker` while building `llvm` at step 2 "checkout".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/113/builds/4526

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

```
Step 2 (checkout) failure: update (failure)
git version 2.34.1
fatal: sha1 file '/home/worker/bolt-worker2/bolt-x86_64-ubuntu-clang/llvm-project/.git/index.lock' write error. Out of diskspace
fatal: sha1 file '/home/worker/bolt-worker2/bolt-x86_64-ubuntu-clang/llvm-project/.git/index.lock' write error. Out of diskspace

```

</details>

https://github.com/llvm/llvm-project/pull/120419