Generics constrained with generic parameters do not resolve

[zacateras]

The issue can be described by the following failing XUnit test:

public class ConstrainedWithGenericParameter<T1, T2>
    where T1 : T2
{
}

[Fact]
public void CanResolveComponentWhenGenericParameterIsConstrainedWithOtherGenericParameter()
{
    var builder = new ContainerBuilder();

    builder.RegisterGeneric(typeof(ConstrainedWithGenericParameter<,>));

    var container = builder.Build();

    Assert.True(container.IsRegistered<ConstrainedWithGenericParameter<int, object>>());
}

It seems that generic parameter constraint compatibility check always returns true for generic constraints stub types like {T1}, {T2}.

I submitted solution to the issue in #819.