[clang] [CIR] Add if statement support (PR #134333)

[Andy Kaylor via cfe-commits]

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@@ -110,6 +111,9 @@ struct MissingFeatures {
   static bool lvalueBaseInfo() { return false; }
   static bool alignCXXRecordDecl() { return false; }
   static bool setNonGC() { return false; }
+  static bool constantFoldsToSimpleInteger() { return false; }
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andykaylor wrote:

This isn't used now. It can be removed.

https://github.com/llvm/llvm-project/pull/134333