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 bug56;

void main()
{
    int[] a;
    a = [1,2,3];
    {int[] b = [4,5,6];}
}