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 virtcall;

extern(C) int printf(char*, ...);

class C
{
    override char[] toString()
    {
        return "overridden";
    }
}

void main()
{
    C c = new C;
    auto s = c.toString();
    printf("%.*s\n", s.length, s.ptr);
}