CxxReact: Silence 'unused lambda capture' warnings in open-source (#22240)

Summary:
This pull request silences build warnings like this in open-source:

```
{snip}/ReactCommon/cxxreact/CxxNativeModule.cpp:134:85: warning: lambda capture 'callId' is not used [-Wunused-lambda-capture]
  messageQueueThread_->runOnQueue([method, params=std::move(params), first, second, callId] () {
```

These are variables used by "fbsystrace", which is not open-sourced.

An  unused statement has been added to the affected files in the `#else` for the `#ifdef WITH_FBSYSTRACE` conditionals
Pull Request resolved: #22240

Differential Revision: D13031358

Pulled By: shergin

fbshipit-source-id: 8ccfc226b65e32abda6abb573f77a6589bd19dcd

Author: empyrical

ReactCommon/cxxreact/CxxNativeModule.cpp

@@ -136,6 +136,8 @@ void CxxNativeModule::invoke(unsigned int reactMethodId, folly::dynamic&& params
     if (callId != -1) {
       fbsystrace_end_async_flow(TRACE_TAG_REACT_APPS, "native", callId);
     }
+  #else
+    (void)(callId);
   #endif
     SystraceSection s(method.name.c_str());
     try {

ReactCommon/cxxreact/NativeToJsBridge.cpp

@@ -161,6 +161,8 @@ void NativeToJsBridge::callFunction(
           "JSCall",
           systraceCookie);
       SystraceSection s("NativeToJsBridge::callFunction", "module", module, "method", method);
+      #else
+      (void)(systraceCookie);
       #endif
       // This is safe because we are running on the executor's thread: it won't
       // destruct until after it's been unregistered (which we check above) and
@@ -191,6 +193,8 @@ void NativeToJsBridge::invokeCallback(double callbackId, folly::dynamic&& argume
           "<callback>",
           systraceCookie);
       SystraceSection s("NativeToJsBridge::invokeCallback");
+      #else
+      (void)(systraceCookie);
       #endif
       executor->invokeCallback(callbackId, arguments);
     });