Add "search" link to bug statistics page

Loading the "All open" link takes a whopping ~10 seconds for me, while I almost always just want to get to the search page. Loading the search page only takes a second for me, so this adds a `[search]` link to the right of the `[report new bug]` link.

At least I hope it does - `bugstats.php` is only mentioned in `posix.mak`, not in `win32.mak`, so I can't test it. @andralex?