Don't try map deep automap with scalar value types

Author: mythz

src/ServiceStack.Text/AutoMappingUtils.cs

@@ -644,7 +644,8 @@ public void Populate(object to, object from,
                                 fromValue = listResult;
                             }
                         }
-                        else if (!toMember.Type.IsNullableType())
+                        else if (!(toMember.Type.IsValueType()
+                                || toMember.Type.IsNullableType()))
                         {
                             var toValue = toMember.Type.CreateInstance();
                             toValue.PopulateWith(fromValue);