Fix Read-After-Write (RAW) dependency violation for ar.ccv in isc_atomic_xadd() and isc_atomic_cmpxchg().
Fix Read-After-Write (RAW) dependency violation for ar.ccv in
isc_atomic_xadd() and isc_atomic_cmpxchg().

Approved by:	dougb@
MFC after:	1 week

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