message: Update ConstantFoldFallbackHook to exclude tf.Case op.
  tf.While, tf.If, and call ops (ops with function calls) were excluded originally.
diff: @@ -87,7 +87,7 @@ LogicalResult ConstantFoldFallbackHook(
  }
  // Do not execute function calls.
  - if (llvm::isa<TF::WhileOp, TF::IfOp, CallOpInterface>(inst)) {
  + if (llvm::isa<TF::WhileOp, TF::CaseOp, TF::IfOp, CallOpInterface>(inst)) {
  return failure();
  }
  