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.

// testcase from bug #199

struct Color {
    uint c;

}

struct Vertex {
    Color c;
}

void main() {
    Color c = {0xffffffff};

    auto v = Vertex(c);

    assert(v.c.c == 0xffffffff);  // fails in LDC
}