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 aa1;

void main()
{
    int[int] aai;
    assert(aai is null);
    aai[0] = 52;
    assert(aai !is null);
    int i = aai[0];
    assert(i == 52);
    aai[32] = 123;
    int j = aai[32];
    assert(i == 52);
    assert(j == 123);
}