tests: added a test verifying the fix for issue #225

Running 'make check' after the fix:
...
TEST tst-ring-spsc-wraparound.so OK  (8.817 s)
...

Reviewed-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>