[llvm] [Exegesis][RISCV] Add RISCV support for llvm-exegesis (PR #89047)

[via llvm-commits]

================
@@ -119,7 +119,7 @@ class CounterGroup {
   virtual void start();
 
   /// Stops the measurement of the event.
-  void stop();
+  virtual void stop();
----------------
AnastasiyaChernikova wrote:

Addressed

https://github.com/llvm/llvm-project/pull/89047