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.

void foo()
{
    version(X86)
    asm
    {
        naked;
        jmp pass;
        hlt;
pass:   ret;
    }
    else version(X86_64)
    asm
    {
        naked;
        jmp pass;
        hlt;
pass:   ret;
    }
    else static assert(0, "todo");
}

void main()
{
    foo();
}