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 bug17;

struct Vec
{
    Vec opAdd(ref Vec b) { return Vec(); }
    Vec opMul(double a) { return Vec(); }
}
void main()
{
    Vec foo;
    Vec bar;
    auto whee=foo+bar*1f;
}