Borrow data for validation

Using this KSY:
```
  - id: one_cat
    type: cat
    valid:
      expr: _._sizeof == 1
```

For C++11 changes this incorrect code:
```
m_one_cat = std::unique_ptr<cat_t>(new cat_t(m__io, this, m__root));
m_one_cat->_read();
{
    // Definition: cat_t* one_cat() { return m_one_cat.get(); }
    std::unique_ptr<cat_t> _ = one_cat();
    if (!(1 == 1)) {
        throw kaitai::validation_expr_error<std::unique_ptr<debug_array_user_t::cat_t>>(one_cat(), _io(), std::string("/seq/0"));
    }
}
```

to this:

```
m_one_cat = std::unique_ptr<cat_t>(new cat_t(m__io, this, m__root));
m_one_cat->_read();
{
    // Definition: cat_t* one_cat() { return m_one_cat.get(); }
    cat_t* _ = one_cat();
    if (!(1 == 1)) {
        throw kaitai::validation_expr_error<debug_array_user_t::cat_t*>(one_cat(), _io(), std::string("/seq/0"));
    }
}
```

shared/src/main/scala/io/kaitai/struct/languages/components/ValidateOps.scala

@@ -15,17 +15,18 @@ trait ValidateOps extends ExceptionNames {
   val typeProvider: ClassTypeProvider
 
   def attrValidate(attr: AttrLikeSpec, valid: ValidationSpec): Unit = {
+    val attrTypeRef = attr.dataType.asNonOwning()
     val itemValue = Identifier.itemExpr(attr.id, attr.cond.repeat)
     valid match {
       case ValidationEq(expected) =>
-        attrValidateExprCompare(attr, Ast.cmpop.Eq, expected, ValidationNotEqualError(attr.dataType))
+        attrValidateExprCompare(attr, Ast.cmpop.Eq, expected, ValidationNotEqualError(attrTypeRef))
       case ValidationMin(min) =>
-        attrValidateExprCompare(attr, Ast.cmpop.GtE, min, ValidationLessThanError(attr.dataType))
+        attrValidateExprCompare(attr, Ast.cmpop.GtE, min, ValidationLessThanError(attrTypeRef))
       case ValidationMax(max) =>
-        attrValidateExprCompare(attr, Ast.cmpop.LtE, max, ValidationGreaterThanError(attr.dataType))
+        attrValidateExprCompare(attr, Ast.cmpop.LtE, max, ValidationGreaterThanError(attrTypeRef))
       case ValidationRange(min, max) =>
-        attrValidateExprCompare(attr, Ast.cmpop.GtE, min, ValidationLessThanError(attr.dataType))
-        attrValidateExprCompare(attr, Ast.cmpop.LtE, max, ValidationGreaterThanError(attr.dataType))
+        attrValidateExprCompare(attr, Ast.cmpop.GtE, min, ValidationLessThanError(attrTypeRef))
+        attrValidateExprCompare(attr, Ast.cmpop.LtE, max, ValidationGreaterThanError(attrTypeRef))
       case ValidationAnyOf(values) =>
         val bigOrExpr = Ast.expr.BoolOp(
           Ast.boolop.Or,
@@ -41,7 +42,7 @@ trait ValidateOps extends ExceptionNames {
         attrValidateExpr(
           attr,
           checkExpr = bigOrExpr,
-          err = ValidationNotAnyOfError(attr.dataType),
+          err = ValidationNotAnyOfError(attrTypeRef),
           errArgs = List(
             itemValue,
             Ast.expr.InternalName(IoIdentifier),
@@ -62,16 +63,19 @@ trait ValidateOps extends ExceptionNames {
         )
       case ValidationExpr(expr) =>
         blockScopeHeader
-        typeProvider._currentIteratorType = Some(attr.dataType)
+        typeProvider._currentIteratorType = Some(attrTypeRef)
+        // Store value of attribute in the temporary variable with a name that is
+        // used for `_` variable, because in expression we refer to current value
+        // using this variable
         handleAssignmentTempVar(
-          attr.dataType,
+          attrTypeRef,
           translator.translate(Ast.expr.Name(Ast.identifier(Identifier.ITERATOR))),
           translator.translate(itemValue)
         )
         attrValidateExpr(
           attr,
           expr,
-          ValidationExprError(attr.dataType),
+          ValidationExprError(attrTypeRef),
           List(
             itemValue,
             Ast.expr.InternalName(IoIdentifier),