abci/client: fix DATA RACE in gRPC client (#3798)

* Remove go func {}()

closes #357

- Remove go func(){}() that caused race condiditon

- To reproduce
	- add -race in make file to `install_abci`
	- Remove `CGO_ENABLED=0` & add -race to `install`

Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>

* remove -race

* fix data race

also, reorder callbacks similarly to socket client

abci/client/grpc_client.go

@@ -230,16 +230,20 @@ func (cli *grpcClient) finishAsyncCall(req *types.Request, res *types.Response)
 
 	// goroutine for callbacks
 	go func() {
-		// Notify reqRes listener if set
-		if cb := reqres.GetCallback(); cb != nil {
-			cb(res)
-		}
+		cli.mtx.Lock()
+		defer cli.mtx.Unlock()
 
 		// Notify client listener if set
 		if cli.resCb != nil {
 			cli.resCb(reqres.Request, res)
 		}
+
+		// Notify reqRes listener if set
+		if cb := reqres.GetCallback(); cb != nil {
+			cb(res)
+		}
 	}()
+
 	return reqres
 }