GlobalPtr.opEquals

{
    GlobalPtr!long x = new long(0);
    assert(x != null);
    x = null;
    assert(x == null);
}

{
    GlobalPtr!long x = new long(123);
    GlobalPtr!long y = new long(123);
    assert(x == x);
    assert(y == y);
    assert(x != y);
}

{
    GlobalPtr!long x;
    GlobalPtr!(const long) y;
    assert(x == x);
    assert(y == y);
    assert(x == y);
}

{
    GlobalPtr!long x = new long(123);
    GlobalPtr!long y = new long(123);
    assert(x == x.element);
    assert(y.element == y);
    assert(x != y.element);
}