Allow internal entity classess/interfaces in .NET Standard 2.0 (nhibernate#3160)

Author: bahusoid

src/NHibernate/Proxy/NHibernateProxyBuilder.cs

@@ -76,17 +76,13 @@ public TypeInfo CreateProxyType(System.Type baseType, IReadOnlyCollection<System
 				interfaces.Add(baseType);
 			}
 
-#if NETFX || NETCOREAPP2_0_OR_GREATER || NETSTANDARD2_1_OR_GREATER
 			var assemblyNamesToIgnoreAccessCheck =
 				new[] {baseType}
 					.Concat(interfaces).Where(i => !i.IsVisible)
 					.Select(i => i.Assembly.GetName().Name)
 					.Distinct();
 			foreach (var a in assemblyNamesToIgnoreAccessCheck)
 				ProxyBuilderHelper.GenerateInstanceOfIgnoresAccessChecksToAttribute(assemblyBuilder, a);
-#else
-			interfaces.RemoveWhere(i => !i.IsVisible);
-#endif
 
 			var typeBuilder = moduleBuilder.DefineType(typeName, typeAttributes, parentType, interfaces.ToArray());