rcu: fix synchronize_rcu() so that kernel-doc works

Fix RCU's synchronize_rcu() so that it looks like a C function, enabling
it to be recognized as a function with kernel-doc annotation.

Warning(linux-2.6.26-git11//kernel/rcupdate.c:81): No description found for parameter 'synchronize_rcu'
Warning(linux-2.6.26-git11//kernel/rcupdate.c:81): No description found for parameter 'call_rcu'

[akpm@linux-foundation.org: fix comment]
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/rcupdate.c

@@ -77,6 +77,7 @@ void wakeme_after_rcu(struct rcu_head  *head)
  * sections are delimited by rcu_read_lock() and rcu_read_unlock(),
  * and may be nested.
  */
+void synchronize_rcu(void);	/* Makes kernel-doc tools happy */
 synchronize_rcu_xxx(synchronize_rcu, call_rcu)
 EXPORT_SYMBOL_GPL(synchronize_rcu);