message: Make MLIREmitter::bindConstant variadic
  This is needed to allow binding to more constant types.
  Tests that exercise this behavior will come in a followup CL.
  In the meantime this does not breaks things.
diff: @@ -67,9 +67,9 @@ struct MLIREmitter {
  /// registered, makes sure the Value is of the proper type.
  MLIREmitter &bind(Bindable e, Value *v);
  /// Constant values can be created on the spot and bound.
  - template <typename SSAConstantType, typename T>
  - MLIREmitter &bindConstant(Bindable e, T value) {
  - return bind(e, builder->create<SSAConstantType>(location, value));
  + template <typename SSAConstantType, typename... Args>
  + MLIREmitter &bindConstant(Bindable e, Args... args) {
  + return bind(e, builder->create<SSAConstantType>(location, args...));
  }
  /// Registers new bindings and type-checks. If a certain Expr type is
  