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 arrays4;

void main()
{
    int[] arr;
    arr ~= 3;
    assert(arr.length == 1);
    assert(arr[0] == 3);
    arr ~= 5;
    assert(arr.length == 2);
    assert(arr[0] == 3);
    assert(arr[1] == 5);
}