Fix for a bugprone-use-after-move warning

Summary:
Fix for a bugprone-use-after-move warning

Saw this on another diff:

```
CLANGTIDY
raised a bugprone-use-after-move warning on
line 163
-
'options' used after it was moved
fbcode/folly/experimental/io/MuxIOThreadPoolExecutor.cpp:129:7: move occurred here
      options_(std::move(options)),
      ^
```

Reviewed By: ot

Differential Revision: D52474932

fbshipit-source-id: 81751cd54f47aa2e6636e903b6efff51d076fc02

folly/experimental/io/MuxIOThreadPoolExecutor.cpp

@@ -159,7 +159,7 @@ MuxIOThreadPoolExecutor::MuxIOThreadPoolExecutor(
 
   setNumThreads(numThreads);
   registerThreadPoolExecutor(this);
-  if (options.enableThreadIdCollection) {
+  if (options_.enableThreadIdCollection) {
     threadIdCollector_ = std::make_unique<ThreadIdWorkerProvider>();
   }