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 strings1;
extern(C) int printf(char*, ...);
void f(char[11] buffer)
{
    printf("%.*s\n", buffer.length, buffer.ptr);
}

void main()
{
    char[11] buffer;
    char[] hello = "hello world";
    {buffer[] = hello[];}
    {f(buffer);}
    {f("eleven char");}
}