address use-after-move lint

Summary:
From D56593397:

'channel' used after it was moved
fbcode/eden/fs/inodes/EdenMount.cpp:2046:43: move occurred here

```
                              channel_2 = std::move(channel)](
                                          ^
```

fbcode/eden/fs/inodes/EdenMount.cpp:2040:25: the use and move are unsequenced, i.e. there is no guarantee about the order in which they are evaluated

```
                        channel->getAddr(),
                        ^
```

Reviewed By: jdelliot

Differential Revision: D56645977

fbshipit-source-id: b12ff23e0eca8e5d6092e871a2cbcd1b3689d66c

eden/fs/inodes/EdenMount.cpp

@@ -2032,12 +2032,15 @@ folly::Future<folly::Unit> EdenMount::fsChannelMount(bool readOnly) {
                   NfsServer::NfsMountInfo mountInfo) mutable {
                 auto [channel, mountdAddr] = std::move(mountInfo);
 #ifndef _WIN32
+                // Channel is later moved. We must assign addr to a local var
+                // to avoid the possibility of a use-after-move bug.
+                auto addr = channel->getAddr();
                 // TODO: teach privhelper or something to mount on Windows
                 return serverState_->getPrivHelper()
                     ->nfsMount(
                         mountPath.view(),
                         mountdAddr,
-                        channel->getAddr(),
+                        addr,
                         readOnly,
                         iosize,
                         useReaddirplus)