rsrv: clarify bucketID locking

Make clear that bucketID is guarded by clientQlock

modules/database/src/ioc/rsrv/camessage.c

@@ -1019,7 +1019,6 @@ struct dbChannel *dbch,
 unsigned    cid
 )
 {
-    static unsigned     bucketID;
     unsigned        *pCID;
     struct channel_in_use   *pchannel;
     int         status;
@@ -1052,6 +1051,7 @@ unsigned    cid
     LOCK_CLIENTQ;
 
     do {
+        static unsigned     bucketID;
         /*
          * bypass read only warning
          */