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 bug77;
import tango.stdc.string;
void main()
{
    size_t len;
    void func2()
    {
        char* prefix = "";

        void func()
        {
        len = strlen(prefix);
        assert(len == 0);
        }

        func();
    }
    func2();
}