SCOLL/BASIC: Fix invalid pSync pointer passed to barrier func

mca_scoll_basic_alltoall() passed (pSync + 1) to barrier function, but
the value of _SHMEM_ALLTOALL_SYNC_SIZE is 1, which made the barrier
function use an invalid memory location. In particular, this location
was not initialized to _SHMEM_SYNC_VALUE, which broke the barrier
algorithm and it did not complete: One PE could read 0 from its peer and
assume the peer already started the barrier, and then write 1 to the
peer. Then, the peer entered the barrier and overwrote the 1 with 0, and
then it waited forever to see '1' in its pSync.

Found with shmem_verifier test suite.

Signed-off-by: Yossi Itigin <yosefe@mellanox.com>

oshmem/mca/scoll/basic/scoll_basic_alltoall.c

@@ -79,7 +79,7 @@ int mca_scoll_basic_alltoall(struct oshmem_group_t *group,
 
     /* Wait for operation completion */
     SCOLL_VERBOSE(14, "[#%d] Wait for operation completion", group->my_pe);
-    rc = BARRIER_FUNC(group, pSync + 1, SCOLL_DEFAULT_ALG);
+    rc = BARRIER_FUNC(group, pSync, SCOLL_DEFAULT_ALG);
 
     /* Restore initial values */
     SCOLL_VERBOSE(12, "PE#%d Restore special synchronization array",