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

[Aiden Grossman via llvm-commits]

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@@ -119,7 +119,7 @@ class CounterGroup {
   virtual void start();
 
   /// Stops the measurement of the event.
-  void stop();
+  virtual void stop();
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boomanaiden154 wrote:

I don't think this is being overriden anywhere anymore. We can probably remove the `virtual` for now.

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