[IR] Remove variadic overload of StructType::setBody. NFC. (#114421)

This is unused in-tree.

Author: jayfoad

llvm/include/llvm/IR/DerivedTypes.h

@@ -330,13 +330,6 @@ class StructType : public Type {
   /// recursive.
   Error checkBody(ArrayRef<Type *> Elements);
 
-  template <typename... Tys>
-  std::enable_if_t<are_base_of<Type, Tys...>::value, void>
-  setBody(Type *elt1, Tys *... elts) {
-    assert(elt1 && "Cannot create a struct type with no elements with this");
-    setBody(ArrayRef<Type *>({elt1, elts...}));
-  }
-
   /// Return true if the specified type is valid as a element type.
   static bool isValidElementType(Type *ElemTy);