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 tangotests.gc1;

void main()
{
    int[] arr;

    for (int i=0; i<100; ++i)
    {
        arr ~= new int[1000];
    }

    printf("arr.length = %u\n", arr.length);
}

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