Fix some unittests for 64-bit asm. They were operating on int variables as if they were longs. This was causing asm1_1 to fail when compiled with -O3 because it was overwriting the spilled value of callee-saved register %rbx, which the runtime was using as a pointer value at the time.

module bar;

class S
{
    int i;
    final int foo()
    {
        return i;
    }
}

void main()
{
    auto s = new S;
    s.i = 42;
    auto dg = &s.foo;
    assert(dg() == 42);
}