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 switch1;

void main()
{
    int i = 2;
    int r;
    switch (i)
    {
    case 1: r+=1; break;
    case 2: r-=2;
    case 3: r=3; break;
    default: r=-1;
    }
    assert(r == 3);
}