Added conditional compile for dynamic JSON buffer.

- WLED_USE_DYNAMIC_JSON
Minor fixes.

wled00/mqtt.cpp

@@ -91,14 +91,19 @@ void onMqttMessage(char* topic, char* payload, AsyncMqttClientMessageProperties
     colorUpdated(CALL_MODE_DIRECT_CHANGE);
   } else if (strcmp_P(topic, PSTR("/api")) == 0) {
     if (payload[0] == '{') { //JSON API
-      //DynamicJsonDocument doc(JSON_BUFFER_SIZE);
+    #ifdef WLED_USE_DYNAMIC_JSON
+      DynamicJsonDocument doc(JSON_BUFFER_SIZE);
+    #else
       while (jsonBufferLock) delay(1);
       jsonBufferLock = true;
       doc.clear();
+    #endif
+
       deserializeJson(doc, payloadStr);
       fileDoc = &doc;
       deserializeState(doc.as<JsonObject>());
       fileDoc = nullptr;
+
       jsonBufferLock = false;
     } else { //HTTP API
       String apireq = "win&";