5045 use atomic_{inc,dec}_* instead of atomic_add_*

@@ -100,11 +100,11 @@
         { "delegations",        KSTAT_DATA_UINT64 },
         { "hits",               KSTAT_DATA_UINT64 },
         { "misses",             KSTAT_DATA_UINT64 }
 };
 
-#define VDCSTAT_BUMP(stat)      atomic_add_64(&vdc_stats.stat.value.ui64, 1);
+#define VDCSTAT_BUMP(stat)      atomic_inc_64(&vdc_stats.stat.value.ui64);
 
 static int
 vdev_cache_offset_compare(const void *a1, const void *a2)
 {
         const vdev_cache_entry_t *ve1 = a1;