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.

struct Color {
  uint c;
  static Color opCall(uint _c) { Color ret; ret.c = _c; return ret; }
}

// run at compile time
static const Color white = Color(0xffffffff);

void main()
{
  assert(white.c == 0xffffffff);
}