[llvm] [NFC][EarlyIfConverter] Replace boolean Predicate for a class (PR #108519)

[Juan Manuel Martinez Caamaño via llvm-commits]

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@@ -122,6 +122,17 @@ class SSAIfConv {
   /// The branch condition determined by analyzeBranch.
   SmallVector<MachineOperand, 4> Cond;
 
+  struct PredicationStrategyBase {
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jmmartinez wrote:

I agree. Updated to `class` for `PredicationStrategyBase` and its derived classes.

https://github.com/llvm/llvm-project/pull/108519