Optimistic spinning is only used by the xadd variant
of rw-semaphores. Make sure that we use the old version
of the __RWSEM_INITIALIZER macro for systems that rely
on the spinlock one, otherwise warnings can be triggered,
such as the following reported on an arm box:

  ipc/ipcns_notifier.c:22:8: warning: excess elements in struct initializer [enabled by default]
  ipc/ipcns_notifier.c:22:8: warning: (near initialization for 'ipcns_chain.rwsem') [enabled by default]
  ipc/ipcns_notifier.c:22:8: warning: excess elements in struct initializer [enabled by default]
  ipc/ipcns_notifier.c:22:8: warning: (near initialization for 'ipcns_chain.rwsem') [enabled by default]
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fusionio.com>
Link: http://lkml.kernel.org/r/1400545677.6399.10.camel@buesod1.americas.hpqcorp.netSigned-off-by: Ingo Molnar <mingo@kernel.org>