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.

class C { void foo() {} }

void main()
{
  C c = new C;
  void delegate() dlg = &c.foo;

  assert(dlg);
}