[td-255] fix compiler error

src/client/src/tscSubquery.c

@@ -1911,13 +1911,12 @@ int32_t tscHandleMultivnodeInsert(SSqlObj *pSql) {
   size_t size = taosArrayGetSize(pCmd->pDataBlocks);
   assert(size > 0);
 
+  pSql->numOfSubs = (uint16_t)size;
   pSql->pSubs = calloc(size, POINTER_BYTES);
   if (pSql->pSubs == NULL) {
     goto _error;
   }
 
-  pSql->numOfSubs = (uint16_t)size;
-
   tscDebug("%p submit data to %" PRIzu " vnode(s)", pSql, size);
 
   SSubqueryState *pState = calloc(1, sizeof(SSubqueryState));